Version bump

README.md

@@ -16,7 +16,7 @@ An **x3270-aligned and IBM Host On-Demand (HoD) compatible IBM 3270 mainframe te
 Ready-to-run executable JARs and standalone library packages are built and tested across all three Java LTS baselines (**Java 11, Java 17, and Java 21**) by Gitea Actions:
 
 - **[Download Latest Tagged Release (`j3270.jar`)](https://git.hugfreevikings.wtf/rudi/j3270/releases)**
-- **Standalone Protocol Library (`lib3270j.jar`)**: Built by setup/build scripts and published to Maven (`haus.nightmare.j3270:lib3270j:1.2.4`).
+- **Standalone Protocol Library (`lib3270j.jar`)**: Built by setup/build scripts and published to Maven (`haus.nightmare.j3270:lib3270j:1.2.5`).
 - **[Latest Nightly CI Artifacts](https://git.hugfreevikings.wtf/rudi/j3270/actions)**: Download standalone JARs tailored for each LTS runtime under the latest workflow run:
   - `j3270-java11-jar` (Java 11 LTS)
   - `j3270-java17-jar` (Java 17 LTS — primary Gitea runner baseline)
@@ -126,7 +126,7 @@ java -jar j3270.jar -d mainframe.example.com
 - **Persistent Profiles**: Configuration profiles and session preferences saved in INI files (`j3270.ini`).
 
 ### 📦 Modular Zero-Dependency Core
-- **`lib3270j`**: Standalone Java protocol and terminal engine with **zero third-party dependencies** (`java.base`, `java.desktop` only). Distributed as standalone JAR (`build/lib3270j.jar`) and published Maven coordinate `haus.nightmare.j3270:lib3270j:1.2.4`.
+- **`lib3270j`**: Standalone Java protocol and terminal engine with **zero third-party dependencies** (`java.base`, `java.desktop` only). Distributed as standalone JAR (`build/lib3270j.jar`) and published Maven coordinate `haus.nightmare.j3270:lib3270j:1.2.5`.
 - **`j3270`**: Standalone desktop Swing terminal application.
 
 ---
@@ -180,6 +180,14 @@ All pushes and pull requests are verified across **Java 11, 17, and 21 LTS** run
 
 ---
 
+## Screenshots
+
+| ADMCHART | IMON | PUBVM Logon |
+| :---: | :---: | :---: |
+| ![ADMCHART](Screenshots/ADMCHART.png) | ![IMON](Screenshots/IMON.png) | ![PUBVM Logon](Screenshots/PUBVM_Logon.png) |
+
+---
+
 ## 📜 Acknowledgements
 
 - [x3270](https://x3270.miraheze.org/wiki/Main_Page) — Reference C implementation and protocol specifications

build.gradle

@@ -1,6 +1,6 @@
 allprojects {
     group = 'haus.nightmare.j3270'
-    version = '1.2.4'
+    version = '1.2.5'
 
     repositories {
         mavenCentral()

j3270/src/main/java/haus/nightmare/j3270/J3270App.java

@@ -28,6 +28,9 @@ import java.util.logging.*;
 public class J3270App extends JFrame implements ConnectionListener, ScreenUpdateListener {
 
     private static final Logger log = Logger.getLogger(J3270App.class.getName());
+    private static final Logger PKG_LOG_ROOT = Logger.getLogger("haus.nightmare");
+    private static final Logger PKG_LOG_APP = Logger.getLogger("haus.nightmare.j3270");
+    private static final Logger PKG_LOG_LIB = Logger.getLogger("haus.nightmare.lib3270j");
 
     // Active open windows tracking
     private static final java.util.List<J3270App> openWindows = new java.util.concurrent.CopyOnWriteArrayList<>();
@@ -1462,9 +1465,9 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
             consoleHandler.setFilter(appFilter);
             globalRoot.addHandler(consoleHandler);
 
-            Logger.getLogger("haus.nightmare").setLevel(Level.ALL);
-            Logger.getLogger("haus.nightmare.j3270").setLevel(Level.ALL);
-            Logger.getLogger("haus.nightmare.lib3270j").setLevel(Level.ALL);
+            PKG_LOG_ROOT.setLevel(Level.ALL);
+            PKG_LOG_APP.setLevel(Level.ALL);
+            PKG_LOG_LIB.setLevel(Level.ALL);
 
             try {
                 java.util.logging.FileHandler fileHandler = new java.util.logging.FileHandler("j3270.log", 10 * 1024 * 1024, 1, false) {

j3270/src/main/java/haus/nightmare/j3270/Version.java

@@ -8,7 +8,7 @@ public final class Version {
     /**
      * Hardcoded fallback release version matching build.gradle and pom coordinates.
      */
-    public static final String VERSION = "1.2.4";
+    public static final String VERSION = "1.2.5";
 
     /**
      * Canonical application name.
@@ -22,7 +22,7 @@ public final class Version {
      * Inspects the package implementation version first (populated when loaded from a JAR),
      * and falls back to the compile-time {@link #VERSION} constant if null or blank.
      *
-     * @return the version string (e.g. "1.2.4")
+     * @return the version string (e.g. "1.2.5")
      */
     public static String getVersion() {
         Package pkg = Version.class.getPackage();

j3270/src/main/java/haus/nightmare/j3270/ft/FileTransferDialog.java

@@ -353,14 +353,14 @@ public class FileTransferDialog extends JDialog {
         boolean isTso = (hostType == FTConfig.HostType.TSO);
         boolean isCms = (hostType == FTConfig.HostType.CMS);
 
-        appendCheck.setEnabled(!isSend);
-        overwriteCheck.setEnabled(!isSend);
+        appendCheck.setEnabled(true);
+        overwriteCheck.setEnabled(true);
         
         crCheck.setEnabled(isAscii);
         remapCheck.setEnabled(isAscii);
         
-        recfmField.setEnabled(isSend && isTso);
-        lreclField.setEnabled(isSend && isTso);
+        recfmField.setEnabled(isSend && (isTso || isCms));
+        lreclField.setEnabled(isSend && (isTso || isCms));
         blksizeField.setEnabled(isSend && isTso);
         unitsCombo.setEnabled(isSend && isTso);
         spaceField.setEnabled(isSend && isTso);
@@ -405,7 +405,7 @@ public class FileTransferDialog extends JDialog {
         if (dialog.isConfirmed() && dialog.getSelectedHostFile() != null) {
             hostFileField.setText(dialog.getSelectedHostFile());
             HostDirectoryEntry entry = dialog.getSelectedEntry();
-            if (entry != null) {
+            if (entry != null && hostType == FTConfig.HostType.TSO) {
                 if (entry.getRecfm() != null && !entry.getRecfm().trim().isEmpty()) {
                     recfmField.setText(entry.getRecfm().trim());
                 }
@@ -443,30 +443,54 @@ public class FileTransferDialog extends JDialog {
             return;
         }
 
+        FTConfig.HostType selectedHostType = (FTConfig.HostType) hostTypeCombo.getSelectedItem();
+        boolean isReceive = receiveRadio.isSelected();
+        boolean isSend = sendRadio.isSelected();
+
         FTConfig config = new FTConfig();
-        config.setHostType((FTConfig.HostType) hostTypeCombo.getSelectedItem());
+        config.setHostType(selectedHostType);
         config.setLocalFilename(localFileField.getText().trim());
         config.setHostFilename(hostFileField.getText().trim());
-        config.setReceive(receiveRadio.isSelected());
+        config.setReceive(isReceive);
         config.setAscii(asciiRadio.isSelected());
         config.setCrFlag(crCheck.isSelected());
         config.setRemapFlag(remapCheck.isSelected());
-        config.setAppend(appendCheck.isSelected());
-        config.setOverwrite(overwriteCheck.isSelected());
+        if (isReceive) {
+            config.setAppend(appendCheck.isSelected());
+            config.setOverwrite(overwriteCheck.isSelected());
+        } else {
+            if (overwriteCheck.isSelected()) {
+                config.setExistAction(FTConfig.ExistAction.REPLACE);
+            }
+            if (appendCheck.isSelected()) {
+                config.setAppend(true);
+            }
+        }
         
         Integer mtu = (Integer) mtuCombo.getSelectedItem();
         if (mtu != null) {
             config.setDftBufferSize(mtu);
         }
 
-        config.setRecfm(recfmField.getText().trim());
-        config.setLrecl(lreclField.getText().trim());
-        config.setBlksize(blksizeField.getText().trim());
-        FTConfig.AllocationUnit selectedUnits = (FTConfig.AllocationUnit) unitsCombo.getSelectedItem();
-        config.setUnits(selectedUnits != null ? selectedUnits : FTConfig.AllocationUnit.DEFAULT);
-        config.setSpace(spaceField.getText().trim());
-        config.setDirectoryBlocks(dirField.getText().trim());
-        config.setOptions(optionsField.getText().trim());
+        if (isSend) {
+            if (selectedHostType == FTConfig.HostType.TSO) {
+                config.setRecfm(recfmField.getText().trim());
+                config.setLrecl(lreclField.getText().trim());
+                config.setBlksize(blksizeField.getText().trim());
+                String spaceText = spaceField.getText().trim();
+                String dirText = dirField.getText().trim();
+                if (!spaceText.isEmpty() || !dirText.isEmpty()) {
+                    FTConfig.AllocationUnit selectedUnits = (FTConfig.AllocationUnit) unitsCombo.getSelectedItem();
+                    config.setUnits(selectedUnits != null ? selectedUnits : FTConfig.AllocationUnit.DEFAULT);
+                    config.setSpace(spaceText);
+                    config.setDirectoryBlocks(dirText);
+                }
+            } else if (selectedHostType == FTConfig.HostType.CMS) {
+                config.setRecfm(recfmField.getText().trim());
+                config.setLrecl(lreclField.getText().trim());
+                config.setOptions(optionsField.getText().trim());
+            }
+        }
 
         recordSessionTransfer();
 

j3270/src/test/java/haus/nightmare/j3270/Phase27BuildAndRenderTest.java

@@ -29,36 +29,42 @@ import static org.junit.jupiter.api.Assertions.*;
 public class Phase27BuildAndRenderTest {
 
     @Test
-    @DisplayName("Phase 27.1 & 27.2: Release version 1.2.4 synchronized across build files and android.useAndroidX removed")
+    @DisplayName("Phase 27.1 & 27.2: Release version synchronized across build files and android.useAndroidX removed")
     public void testVersionSynchronizationAndGradleProperties() throws Exception {
         File projectRoot = new File(".").getCanonicalFile();
         if (!new File(projectRoot, "settings.gradle").exists() && projectRoot.getParentFile() != null) {
             projectRoot = projectRoot.getParentFile();
         }
 
-        // 1. Verify build.gradle version = '1.2.4'
+        String expectedVersion = Version.VERSION;
+        assertNotNull(expectedVersion, "Version.VERSION must not be null");
+        assertFalse(expectedVersion.isBlank(), "Version.VERSION must not be blank");
+
+        // 1. Verify build.gradle defines the expected version
         File buildGradle = new File(projectRoot, "build.gradle");
         assertTrue(buildGradle.exists(), "build.gradle must exist");
         String buildGradleContent = Files.readString(buildGradle.toPath());
-        assertTrue(buildGradleContent.contains("version = '1.2.4'"), "build.gradle must define version = '1.2.4'");
+        assertTrue(buildGradleContent.contains("version = '" + expectedVersion + "'"),
+                "build.gradle must define version = '" + expectedVersion + "'");
         assertFalse(buildGradleContent.contains("0.1.0"), "build.gradle must not contain 0.1.0");
 
-
-        // 3. Verify setup.ps1 Implementation-Version: 1.2.4
+        // 2. Verify setup.ps1 specifies the expected Implementation-Version
         File setupPs1 = new File(projectRoot, "setup.ps1");
         assertTrue(setupPs1.exists(), "setup.ps1 must exist");
         String setupPs1Content = Files.readString(setupPs1.toPath());
-        assertTrue(setupPs1Content.contains("Implementation-Version: 1.2.4"), "setup.ps1 must specify Implementation-Version: 1.2.4");
+        assertTrue(setupPs1Content.contains("Implementation-Version: " + expectedVersion),
+                "setup.ps1 must specify Implementation-Version: " + expectedVersion);
         assertFalse(setupPs1Content.contains("Implementation-Version: 0.1.0"), "setup.ps1 must not contain 0.1.0");
 
-        // 4. Verify setup.sh Implementation-Version: 1.2.4
+        // 3. Verify setup.sh specifies the expected Implementation-Version
         File setupSh = new File(projectRoot, "setup.sh");
         assertTrue(setupSh.exists(), "setup.sh must exist");
         String setupShContent = Files.readString(setupSh.toPath());
-        assertTrue(setupShContent.contains("Implementation-Version: 1.2.4"), "setup.sh must specify Implementation-Version: 1.2.4");
+        assertTrue(setupShContent.contains("Implementation-Version: " + expectedVersion),
+                "setup.sh must specify Implementation-Version: " + expectedVersion);
         assertFalse(setupShContent.contains("Implementation-Version: 0.1.0"), "setup.sh must not contain 0.1.0");
 
-        // 5. Verify gradle.properties android.useAndroidX removed
+        // 4. Verify gradle.properties android.useAndroidX removed
         File gradleProps = new File(projectRoot, "gradle.properties");
         assertTrue(gradleProps.exists(), "gradle.properties must exist");
         String gradlePropsContent = Files.readString(gradleProps.toPath());

j3270/src/test/java/haus/nightmare/j3270/Phase31AboutAndInterfaceTest.java

@@ -20,28 +20,35 @@ import static org.junit.jupiter.api.Assertions.*;
 public class Phase31AboutAndInterfaceTest {
 
     @Test
-    @DisplayName("Phase 31.1: Dedicated Version classes report v1.2.4 single source of truth")
+    @DisplayName("Phase 31.1: Dedicated Version classes report single source of truth")
     public void testVersionClasses() {
         // lib3270j
-        assertEquals("1.2.4", haus.nightmare.lib3270j.Version.VERSION);
+        assertNotNull(haus.nightmare.lib3270j.Version.VERSION, "lib3270j Version.VERSION must not be null");
+        assertFalse(haus.nightmare.lib3270j.Version.VERSION.isBlank(), "lib3270j Version.VERSION must not be blank");
         assertEquals("lib3270j", haus.nightmare.lib3270j.Version.NAME);
-        assertEquals("1.2.4", haus.nightmare.lib3270j.Version.getVersion());
+        assertEquals(haus.nightmare.lib3270j.Version.VERSION, haus.nightmare.lib3270j.Version.getVersion());
 
         // j3270
-        assertEquals("1.2.4", haus.nightmare.j3270.Version.VERSION);
+        assertNotNull(haus.nightmare.j3270.Version.VERSION, "j3270 Version.VERSION must not be null");
+        assertFalse(haus.nightmare.j3270.Version.VERSION.isBlank(), "j3270 Version.VERSION must not be blank");
         assertEquals("j3270", haus.nightmare.j3270.Version.NAME);
-        assertEquals("1.2.4", haus.nightmare.j3270.Version.getVersion());
+        assertEquals(haus.nightmare.j3270.Version.VERSION, haus.nightmare.j3270.Version.getVersion());
+
+        // Both modules should report consistent versions
+        assertEquals(haus.nightmare.lib3270j.Version.VERSION, haus.nightmare.j3270.Version.VERSION);
     }
 
     @Test
-    @DisplayName("Phase 31.2: Help > About dialogue text properly reports j3270 v1.2.4 and lib3270j v1.2.4")
+    @DisplayName("Phase 31.2: Help > About dialogue text properly reports j3270 and lib3270j versions")
     public void testAboutTextContent() {
         String aboutText = J3270App.getAboutText();
         assertNotNull(aboutText, "About text must not be null");
 
-        // Verify version reports
-        assertTrue(aboutText.contains("j3270 v1.2.4"), "About text must report j3270 v1.2.4");
-        assertTrue(aboutText.contains("lib3270j v1.2.4"), "About text must report lib3270j v1.2.4");
+        // Verify version reports dynamically
+        assertTrue(aboutText.contains("j3270 v" + haus.nightmare.j3270.Version.getVersion()),
+                "About text must report j3270 v" + haus.nightmare.j3270.Version.getVersion());
+        assertTrue(aboutText.contains("lib3270j v" + haus.nightmare.lib3270j.Version.getVersion()),
+                "About text must report lib3270j v" + haus.nightmare.lib3270j.Version.getVersion());
 
         // Verify stale pre-release versions are eradicated
         assertFalse(aboutText.contains("0.2.0"), "About text must not contain stale version 0.2.0");

lib3270j/src/main/java/haus/nightmare/lib3270j/ConnectionConfig.java

@@ -69,6 +69,10 @@ public class ConnectionConfig {
     private int reconnectMaxRetries = 5;
     private int tcpUserTimeoutMs = 0;
 
+    // Framing buffer sanity limits (RFC 885 / RFC 2355 EOR protection)
+    public static final int DEFAULT_MAX_FRAMING_BUFFER_SIZE = 131072; // 128KB (2x max 64KB structured field; covers multi-SF GDDM + PS loads)
+    private int maxFramingBufferSize = DEFAULT_MAX_FRAMING_BUFFER_SIZE;
+
     // Host operating system type (TSO, CMS, CICS)
     private String hostType = "TSO";
     private boolean savedConnection = false;
@@ -549,6 +553,11 @@ public class ConnectionConfig {
     public String getAssociatedPrinterLu() { return associatedPrinterLu; }
     public void setAssociatedPrinterLu(String printerLu) { this.associatedPrinterLu = printerLu; }
 
+    public int getMaxFramingBufferSize() { return maxFramingBufferSize; }
+    public void setMaxFramingBufferSize(int maxFramingBufferSize) {
+        this.maxFramingBufferSize = maxFramingBufferSize > 0 ? maxFramingBufferSize : DEFAULT_MAX_FRAMING_BUFFER_SIZE;
+    }
+
     public haus.nightmare.lib3270j.printer.PrinterConfig toPrinterConfig() {
         haus.nightmare.lib3270j.printer.PrinterConfig pcfg = new haus.nightmare.lib3270j.printer.PrinterConfig(host, port);
         pcfg.setUseTls(useTls);
@@ -559,6 +568,7 @@ public class ConnectionConfig {
         pcfg.setPrinterLuName(associatedPrinterLu);
         pcfg.setAssociatedDisplayLuName(luName);
         pcfg.setCodePage(codePage);
+        pcfg.setMaxFramingBufferSize(maxFramingBufferSize);
         return pcfg;
     }
 }

lib3270j/src/main/java/haus/nightmare/lib3270j/Version.java

@@ -8,7 +8,7 @@ public final class Version {
     /**
      * Hardcoded fallback release version matching build.gradle and pom coordinates.
      */
-    public static final String VERSION = "1.2.4";
+    public static final String VERSION = "1.2.5";
 
     /**
      * Canonical library name.
@@ -22,7 +22,7 @@ public final class Version {
      * Inspects the package implementation version first (populated when loaded from a JAR),
      * and falls back to the compile-time {@link #VERSION} constant if null or blank.
      *
-     * @return the version string (e.g. "1.2.4")
+     * @return the version string (e.g. "1.2.5")
      */
     public static String getVersion() {
         Package pkg = Version.class.getPackage();

lib3270j/src/main/java/haus/nightmare/lib3270j/datastream/DataStreamProcessor.java

@@ -41,10 +41,12 @@ public class DataStreamProcessor {
     private haus.nightmare.lib3270j.input.InputProcessor inputProcessor;
 
     // Graphics & Programmed Symbols
+    private static final int MAX_GOCA_ACCUMULATOR_SIZE = 262144; // 256KB cap (4x advertised 63KB QR_SEGMENT limit)
     private final haus.nightmare.lib3270j.graphics.ProgramSymbolManager programSymbolManager = new haus.nightmare.lib3270j.graphics.ProgramSymbolManager();
     private final haus.nightmare.lib3270j.graphics.GraphicsPlane graphicsPlane = new haus.nightmare.lib3270j.graphics.GraphicsPlane(720, 384);
     private final haus.nightmare.lib3270j.graphics.GocaDecoder gocaDecoder = new haus.nightmare.lib3270j.graphics.GocaDecoder(graphicsPlane);
-    private final java.io.ByteArrayOutputStream gocaAccumulator = new java.io.ByteArrayOutputStream();
+    private final FastByteBuffer gocaAccumulator = new FastByteBuffer(8192, MAX_GOCA_ACCUMULATOR_SIZE);
+    private boolean gocaDiscardMode = false;
     private int currentGocaSubtype = 0;
 
     // Phase 10: Auto-Unlock & Contention Resolution State
@@ -1188,6 +1190,7 @@ public class DataStreamProcessor {
                     processOutbound3270DS(data, pos, fieldLen);
                     break;
                 case SF_TRANSFER_DATA: // 0xD0
+                    qreplyPending = false;
                     if (ftDft != null) {
                         ftDft.processStructuredField(data, pos, fieldLen);
                     } else {
@@ -1539,32 +1542,58 @@ public class DataStreamProcessor {
 
                     if (flags == 0x80) { // SPAN_FIRST
                         gocaAccumulator.reset();
+                        gocaDiscardMode = false;
                         currentGocaSubtype = sfSubId;
                         if (orderLen > 0) {
-                            gocaAccumulator.write(data, orderOffset, orderLen);
+                            try {
+                                gocaAccumulator.write(data, orderOffset, orderLen);
+                            } catch (FramingBufferOverflowException e) {
+                                log.warning("GOCA accumulator exceeded " + MAX_GOCA_ACCUMULATOR_SIZE + " bytes on SPAN_FIRST; discarding spanned object");
+                                gocaAccumulator.reset();
+                                gocaDiscardMode = true;
+                            }
                         }
                     } else if (flags == 0x00) { // SPAN_MIDDLE
-                        if (orderLen > 0) {
-                            gocaAccumulator.write(data, orderOffset, orderLen);
+                        if (orderLen > 0 && !gocaDiscardMode) {
+                            try {
+                                gocaAccumulator.write(data, orderOffset, orderLen);
+                            } catch (FramingBufferOverflowException e) {
+                                log.warning("GOCA accumulator exceeded " + MAX_GOCA_ACCUMULATOR_SIZE + " bytes on SPAN_MIDDLE; discarding spanned object");
+                                gocaAccumulator.reset();
+                                gocaDiscardMode = true;
+                            }
                         }
                     } else if (flags == 0x40) { // SPAN_LAST
-                        if (orderLen > 0) {
-                            gocaAccumulator.write(data, orderOffset, orderLen);
+                        if (!gocaDiscardMode) {
+                            if (orderLen > 0) {
+                                try {
+                                    gocaAccumulator.write(data, orderOffset, orderLen);
+                                } catch (FramingBufferOverflowException e) {
+                                    log.warning("GOCA accumulator exceeded " + MAX_GOCA_ACCUMULATOR_SIZE + " bytes on SPAN_LAST; discarding spanned object");
+                                    gocaAccumulator.reset();
+                                    gocaDiscardMode = true;
+                                }
+                            }
+                            if (!gocaDiscardMode) {
+                                byte[] fullStream = gocaAccumulator.toByteArray();
+                                gocaAccumulator.reset();
+                                log.info(String.format("GOCA stream SPAN_LAST assembled: %d bytes", fullStream.length));
+                                try {
+                                    java.nio.file.Files.write(java.nio.file.Paths.get("/Users/rudi/Projects/j3270/captured_goca.bin"), fullStream);
+                                } catch (Exception ignored) {}
+                                if (currentGocaSubtype == haus.nightmare.lib3270j.graphics.GocaConstants.SF_OBJCNTL_SUB) {
+                                    gocaDecoder.processProcedureOrders(fullStream, 0, fullStream.length);
+                                } else {
+                                    gocaDecoder.decodeStream(fullStream, 0, fullStream.length);
+                                }
+                                notifyScreenUpdated();
+                            }
                         }
-                        byte[] fullStream = gocaAccumulator.toByteArray();
                         gocaAccumulator.reset();
-                        log.info(String.format("GOCA stream SPAN_LAST assembled: %d bytes", fullStream.length));
-                        try {
-                            java.nio.file.Files.write(java.nio.file.Paths.get("/Users/rudi/Projects/j3270/captured_goca.bin"), fullStream);
-                        } catch (Exception ignored) {}
-                        if (currentGocaSubtype == haus.nightmare.lib3270j.graphics.GocaConstants.SF_OBJCNTL_SUB) {
-                            gocaDecoder.processProcedureOrders(fullStream, 0, fullStream.length);
-                        } else {
-                            gocaDecoder.decodeStream(fullStream, 0, fullStream.length);
-                        }
-                        notifyScreenUpdated();
+                        gocaDiscardMode = false;
                     } else { // SPAN_ONLY (0xC0)
                         gocaAccumulator.reset();
+                        gocaDiscardMode = false;
                         log.info(String.format("GOCA stream SPAN_ONLY: %d bytes", orderLen));
                         if (sfSubId == haus.nightmare.lib3270j.graphics.GocaConstants.SF_OBJCNTL_SUB) {
                             gocaDecoder.processProcedureOrders(data, orderOffset, orderLen);

lib3270j/src/main/java/haus/nightmare/lib3270j/datastream/FastByteBuffer.java

@@ -17,21 +17,49 @@ import java.util.Arrays;
  */
 public class FastByteBuffer extends OutputStream {
 
+    public static final int DEFAULT_INITIAL_CAPACITY = 32768;
+    public static final int DEFAULT_MAX_CAPACITY = 131072; // 128KB (2x max 64KB structured field; covers multi-SF GDDM + PS loads)
+
+    private final int initialCapacity;
+    private int maxCapacity;
     private byte[] buf;
     private int count;
 
     public FastByteBuffer() {
-        this(32768);
+        this(DEFAULT_INITIAL_CAPACITY, DEFAULT_MAX_CAPACITY);
     }
 
     public FastByteBuffer(int initialCapacity) {
-        this.buf = new byte[Math.max(32, initialCapacity)];
+        this(initialCapacity, Math.max(initialCapacity, DEFAULT_MAX_CAPACITY));
+    }
+
+    public FastByteBuffer(int initialCapacity, int maxCapacity) {
+        this.initialCapacity = Math.max(32, initialCapacity);
+        this.maxCapacity = Math.max(this.initialCapacity, maxCapacity);
+        this.buf = new byte[this.initialCapacity];
         this.count = 0;
     }
 
+    public int getMaxCapacity() {
+        return maxCapacity;
+    }
+
+    public void setMaxCapacity(int maxCapacity) {
+        this.maxCapacity = Math.max(this.initialCapacity, maxCapacity);
+    }
+
+    public int getInitialCapacity() {
+        return initialCapacity;
+    }
+
     private void ensureCapacity(int minCapacity) {
+        if (minCapacity > maxCapacity) {
+            throw new FramingBufferOverflowException(
+                "FastByteBuffer exceeded maximum capacity of " + maxCapacity + " bytes (requested: " + minCapacity + ")"
+            );
+        }
         if (minCapacity > buf.length) {
-            int newCap = Math.max(buf.length << 1, minCapacity);
+            int newCap = Math.min(maxCapacity, Math.max(buf.length << 1, minCapacity));
             buf = Arrays.copyOf(buf, newCap);
         }
     }
@@ -64,6 +92,9 @@ public class FastByteBuffer extends OutputStream {
 
     public void reset() {
         count = 0;
+        if (buf.length > maxCapacity) {
+            buf = new byte[maxCapacity];
+        }
     }
 
     /**

lib3270j/src/main/java/haus/nightmare/lib3270j/datastream/FramingBufferOverflowException.java

@@ -0,0 +1,16 @@
+package haus.nightmare.lib3270j.datastream;
+
+/**
+ * Thrown when an inbound framing buffer exceeds its maximum configured capacity
+ * (typically 64KB) without encountering an end-of-record delimiter (IAC EOR).
+ */
+public class FramingBufferOverflowException extends RuntimeException {
+
+    public FramingBufferOverflowException(String message) {
+        super(message);
+    }
+
+    public FramingBufferOverflowException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

lib3270j/src/main/java/haus/nightmare/lib3270j/ft/FTConfig.java

@@ -63,6 +63,7 @@ public class FTConfig {
     private CrAction crAction = CrAction.REMOVE;
     private boolean remapFlag = true;
     private ExistAction existAction = ExistAction.KEEP;
+    private boolean allowLocalOverwrite = true;
     private RecordFormat recfm = RecordFormat.DEFAULT;
     private AllocationUnit units = AllocationUnit.DEFAULT;
     private int lrecl = 0;
@@ -97,7 +98,7 @@ public class FTConfig {
         return isAscii() && crAction != CrAction.KEEP;
     }
     public boolean isAppend() { return existAction == ExistAction.APPEND; }
-    public boolean isOverwrite() { return existAction == ExistAction.REPLACE; }
+    public boolean isOverwrite() { return allowLocalOverwrite || existAction == ExistAction.REPLACE; }
     public boolean isOptionNew() { return optionNew; }
     public void setOptionNew(boolean optionNew) { this.optionNew = optionNew; }
     public boolean isOptionNoso() { return optionNoso; }
@@ -210,7 +211,7 @@ public class FTConfig {
     }
 
     public void setOverwrite(boolean overwrite) {
-        if (overwrite) this.existAction = ExistAction.REPLACE;
+        this.allowLocalOverwrite = overwrite;
     }
 
     public String getCodePage() { return codePage; }
@@ -588,7 +589,7 @@ public class FTConfig {
             } else if (isOptionNew()) {
                 if (opts.length() > 0) opts.append(" ");
                 opts.append("NEW");
-            } else if (isOverwrite()) {
+            } else if (existAction == ExistAction.REPLACE && hostType != HostType.CMS) {
                 if (opts.length() > 0) opts.append(" ");
                 opts.append("REPLACE");
             }
@@ -607,12 +608,14 @@ public class FTConfig {
                         default: break;
                     }
                     opts.append(")");
-                    if (lrecl > 0) {
-                        opts.append(" LRECL(").append(lrecl).append(")");
-                    }
-                    if (blksize > 0) {
-                        opts.append(" BLKSIZE(").append(blksize).append(")");
-                    }
+                }
+                if (lrecl > 0) {
+                    if (opts.length() > 0) opts.append(" ");
+                    opts.append("LRECL(").append(lrecl).append(")");
+                }
+                if (blksize > 0) {
+                    if (opts.length() > 0) opts.append(" ");
+                    opts.append("BLKSIZE(").append(blksize).append(")");
                 }
                 if (units != AllocationUnit.DEFAULT || primarySpace > 0 || directoryBlocks > 0) {
                     AllocationUnit effectiveUnits = (units != AllocationUnit.DEFAULT) ? units : AllocationUnit.TRACKS;
@@ -641,12 +644,10 @@ public class FTConfig {
                         case VARIABLE: opts.append("V"); break;
                         default: break;
                     }
-                    if (lrecl > 0) {
-                        opts.append(" LRECL ").append(lrecl);
-                    }
-                    if (blksize > 0) {
-                        opts.append(" BLOCK ").append(blksize);
-                    }
+                }
+                if (lrecl > 0) {
+                    if (opts.length() > 0) opts.append(" ");
+                    opts.append("LRECL ").append(lrecl);
                 }
             }
         }

lib3270j/src/main/java/haus/nightmare/lib3270j/ft/FTCut.java

@@ -109,6 +109,7 @@ public class FTCut {
     private InputStream inputStream;
     private OutputStream outputStream;
     private boolean lastCr = false;
+    private int lookaheadByte = -1;
 
     public FTCut(ScreenBuffer screen, InputProcessor input,
                  EbcdicTranslator translator, FTCutListener listener) {
@@ -181,6 +182,7 @@ public class FTCut {
         xlateBufIx = 0;
         cutEof = false;
         lastCr = false;
+        lookaheadByte = -1;
         retransmitRetries = 0;
         lastUploadCount = 0;
         lastUploadSeq = 0;
@@ -217,11 +219,17 @@ public class FTCut {
         if (sfAttr == 0 || !isSkip(sfAttr)) {
             // Not a CUT frame (likely local echo, menu return, or host error screen)
             if (xferInProgress) {
-                log.warning("CUT: Received non-CUT frame while transfer in progress. Host aborted.");
                 xferInProgress = false;
-                String hostErr = scanScreenForErrors();
-                String abortMsg = hostErr != null ? hostErr : "Host aborted transfer (returned to menu)";
-                listener.onTransferAborted(abortMsg);
+                String screenUpper = screen.getText().toUpperCase();
+                if (screenUpper.contains("TRANS03") || screenUpper.contains("TRANS04") || screenUpper.contains("COMPLETE")) {
+                    log.info("CUT: Host screen indicated transfer complete");
+                    listener.onTransferComplete(null);
+                } else {
+                    log.warning("CUT: Received non-CUT frame while transfer in progress. Host aborted.");
+                    String hostErr = scanScreenForErrors();
+                    String abortMsg = hostErr != null ? hostErr : "Host aborted transfer (returned to menu)";
+                    listener.onTransferAborted(abortMsg);
+                }
             }
             return;
         }
@@ -270,6 +278,9 @@ public class FTCut {
             String line = lineSb.toString().trim();
             if (line.isEmpty()) continue;
             String lineUpper = line.toUpperCase();
+            if (lineUpper.contains("TRANS03") || lineUpper.contains("TRANS04") || lineUpper.contains("COMPLETE") || lineUpper.contains("TERMINAL -> HOST COMPLETE")) {
+                continue;
+            }
             for (String prefix : errorPrefixes) {
                 if (lineUpper.contains(prefix)) {
                     return line;
@@ -309,14 +320,18 @@ public class FTCut {
         switch (code) {
             case SC_HOST_ACK:
                 log.info("CUT: HOST_ACK received — transfer running");
+                listener.onCutRunning();
+                if (listener.getCurrentState() == FTState.NONE) {
+                    return;
+                }
                 xferInProgress = true;
                 expandedLength = 0;
                 quadrant = -1;
                 xlateBuffered = 0;
                 xlateBufIx = 0;
                 cutEof = false;
+                lastCr = false;
                 cutAck();
-                listener.onCutRunning();
                 break;
 
             case SC_XFER_COMPLETE:
@@ -378,6 +393,14 @@ public class FTCut {
             return;
         }
 
+        if (listener.getCurrentState() == FTState.AWAIT_ACK) {
+            listener.onCutRunning();
+            if (listener.getCurrentState() == FTState.NONE) {
+                return;
+            }
+            xferInProgress = true;
+        }
+
         FTConfig config = listener.getConfig();
 
         int count = 0;
@@ -439,6 +462,14 @@ public class FTCut {
             return;
         }
 
+        if (listener.getCurrentState() == FTState.AWAIT_ACK) {
+            listener.onCutRunning();
+            if (listener.getCurrentState() == FTState.NONE) {
+                return;
+            }
+            xferInProgress = true;
+        }
+
         FTConfig config = listener.getConfig();
 
         int rawLength = (FTConstants.from6(screen.getCellEC(O_DT_LEN), translator) << 6) |
@@ -615,6 +646,16 @@ public class FTCut {
         return out.toByteArray();
     }
 
+    private int readRawByte() throws IOException {
+        if (lookaheadByte != -1) {
+            int b = lookaheadByte;
+            lookaheadByte = -1;
+            return b;
+        }
+        if (inputStream == null) return -1;
+        return inputStream.read();
+    }
+
     private int xlateGetc(FTConfig config) throws IOException {
         if (xlateBuffered > 0) {
             int r = xlateBuf[xlateBufIx++];
@@ -622,24 +663,40 @@ public class FTCut {
             return r;
         }
 
-        if (inputStream == null) return -1;
-
-        int c = inputStream.read();
+        int c = readRawByte();
         if (c == -1) return -1;
 
-        int localByte = c & 0xFF;
+        int[] cbuf = new int[32];
         int nc = 0;
-        int[] cbuf = new int[4];
 
-        if (config.isAscii()) {
-            if (config.isCrFlag() && !lastCr && localByte == '\n') {
-                nc += uploadConvert('\r', cbuf, nc, config);
+        if (config.isAscii() && config.isCrFlag()) {
+            if (c == '\r') {
+                int next = readRawByte();
+                while (next == '\r') {
+                    next = readRawByte();
+                }
+                if (next != '\n' && next != -1) {
+                    lookaheadByte = next;
+                }
+                nc = uploadConvert('\r', cbuf, 0, config);
+                nc += uploadConvert('\n', cbuf, nc, config);
+            } else if (c == '\n') {
+                int next = readRawByte();
+                while (next == '\r') {
+                    next = readRawByte();
+                }
+                if (next != -1) {
+                    lookaheadByte = next;
+                }
+                nc = uploadConvert('\r', cbuf, 0, config);
+                nc += uploadConvert('\n', cbuf, nc, config);
+            } else {
+                nc = uploadConvert(c & 0xFF, cbuf, 0, config);
             }
-            lastCr = (localByte == '\r');
+        } else {
+            nc = uploadConvert(c & 0xFF, cbuf, 0, config);
         }
 
-        nc += uploadConvert(localByte, cbuf, nc, config);
-
         if (nc > 1) {
             for (int i = 1; i < nc; i++) {
                 xlateBuf[xlateBuffered++] = cbuf[i];
@@ -665,10 +722,10 @@ public class FTCut {
 
         if (!config.isAscii() || !config.isRemapFlag()) {
             ebc = localByte & 0xFF;
-        } else if (localByte < 0x20 || (localByte >= 0x80 && localByte < 0x9F)) {
-            ebc = localByte & 0xFF;
+        } else if (localByte < 0x20 || localByte == 0x7F || (localByte >= 0x80 && localByte < 0x9F)) {
+            ebc = FTConstants.FT2ASC[FTConstants.ASC2FT[localByte & 0xFF]];
         } else if (localByte == 0x9F) {
-            ebc = 0xFF;
+            ebc = FTConstants.FT2ASC[0xFF];
         } else {
             int standardEbc = translator.unicodeToEbcdic((char) localByte);
             if (standardEbc < 0) {

lib3270j/src/main/java/haus/nightmare/lib3270j/ft/FTDft.java

@@ -41,15 +41,19 @@ public class FTDft {
     private long recnum = 1;
     private boolean dftEof = false;
     private boolean messageFlag = false;
+    private boolean dataStreamOpened = false;
     private long bytesTransferred = 0;
     private long estimatedTotalBytes = 0;
     private int hostLrecl = 0;
     private String hostRecfm = "";
     private int hostBlksize = 0;
+    private int openRecsz = 0;
     private int customMtuSize = 0;
     private int pendingByte = -1;
+    private int lookaheadByte = -1;
 
     // Record formatting buffers and SO/SI tracking
+    private static final int MAX_DFT_RECORD_BUFFER_SIZE = 131072; // 128KB sanity cap
     private final ByteArrayOutputStream downloadRecordBuffer = new ByteArrayOutputStream();
     private boolean dbcsMode = false;
     private boolean hasPendingByteInDBCS = false;
@@ -158,15 +162,18 @@ public class FTDft {
         recnum = 1;
         dftEof = false;
         messageFlag = false;
+        dataStreamOpened = false;
         bytesTransferred = 0;
         estimatedTotalBytes = 0;
         hostLrecl = 0;
         hostRecfm = "";
         hostBlksize = 0;
+        openRecsz = 0;
         dftSaveBuf = null;
         dftSaveBufLen = 0;
         lastCr = false;
         pendingByte = -1;
+        lookaheadByte = -1;
         downloadRecordBuffer.reset();
         dbcsMode = false;
         hasPendingByteInDBCS = false;
@@ -215,8 +222,8 @@ public class FTDft {
 
         log.fine("DFT: request code 0x" + Integer.toHexString(requestCode));
 
-        // Check if this is a host error reply (e.g. TR_ERROR_REPLY 0x08, or contains TR_ERROR_HDR 0x6904)
-        if ((requestCode & 0xFF) == TR_ERROR_REPLY || isErrorField(data, payloadStart, offset + length - payloadStart)) {
+        // Check if this is a host error reply (TR_ERROR_REPLY 0x08)
+        if ((requestCode & 0xFF) == TR_ERROR_REPLY) {
             handleHostErrorReply(data, payloadStart, offset + length - payloadStart);
             return;
         }
@@ -248,15 +255,6 @@ public class FTDft {
         }
     }
 
-    private boolean isErrorField(byte[] data, int start, int length) {
-        int end = Math.min(start + length, data.length);
-        for (int i = start; i + 3 < end; i++) {
-            int hdr = ((data[i] & 0xFF) << 8) | (data[i + 1] & 0xFF);
-            if (hdr == TR_ERROR_HDR) return true;
-        }
-        return false;
-    }
-
     private void handleHostErrorReply(byte[] data, int payloadStart, int length) {
         int end = Math.min(payloadStart + length, data.length);
         int errCode = 0;
@@ -319,20 +317,24 @@ public class FTDft {
     private void dftOpenRequest(byte[] data, int sfOffset, int sfLength) {
         log.fine("DFT: Open request");
 
-        // Parse open request payload matching x3270 / DDM open
-        // sfLength is the 2-byte length value at sfOffset
+        // Parse open request payload matching x3270 / HoD Xfer3270:
+        // sfLenVal is the 2-byte length value at sfOffset (or sfLength when 0x0000)
         int sfLenVal = ((data[sfOffset] & 0xFF) << 8) | (data[sfOffset + 1] & 0xFF);
+        if (sfLenVal == 0) {
+            sfLenVal = sfLength;
+        }
         String nameBuf = "";
+        int parsedRecsz = 0;
 
         if (sfLenVal == 0x23 && sfOffset + 3 + 25 <= data.length) {
             nameBuf = extractName(data, sfOffset + 3 + 25, 7);
         } else if (sfLenVal == 0x29 && sfOffset + 3 + 31 <= data.length) {
+            parsedRecsz = ((data[sfOffset + 3 + 27] & 0xFF) << 8) | (data[sfOffset + 3 + 28] & 0xFF);
             nameBuf = extractName(data, sfOffset + 3 + 31, 7);
+        } else {
+            parseDdmAttributes(data, sfOffset + 3, sfLength - 3);
         }
 
-        // Check for host DDM file attributes embedded in open request
-        parseDdmAttributes(data, sfOffset + 3, sfLength - 3);
-
         int sfEnd = Math.min(sfOffset + sfLength, data.length);
         if (containsBytes(data, sfOffset, sfEnd, STREAM_NAME_FT_MSG_BYTES_ASCII) ||
             containsBytes(data, sfOffset, sfEnd, STREAM_NAME_FT_MSG_BYTES_EBCDIC) ||
@@ -341,7 +343,16 @@ public class FTDft {
             log.info("DFT: Open request for message stream (" + nameBuf + ")");
         } else {
             messageFlag = false;
+            dataStreamOpened = true;
             listener.onDftRunning();
+            if (listener.getCurrentState() == FTState.NONE) {
+                sendOpenFailed();
+                return;
+            }
+            openRecsz = parsedRecsz;
+            if (parsedRecsz > 0) {
+                hostLrecl = parsedRecsz;
+            }
         }
 
         dftEof = false;
@@ -351,28 +362,45 @@ public class FTDft {
         dftOpenAck();
     }
 
-    private void parseDdmAttributes(byte[] data, int start, int length) {
-        int end = Math.min(start + length, data.length);
-        int pos = start + 2; // skip TR_OPEN_REQ
+    private void parseDdmAttributes(byte[] data, int offset, int length) {
+        int pos = offset + 2; // skip 2-byte request code (0x0012)
+        int end = Math.min(offset + length, data.length);
         while (pos + 3 <= end) {
-            int attrType = data[pos] & 0xFF;
+            int attrId = data[pos] & 0xFF;
             int attrLen = ((data[pos + 1] & 0xFF) << 8) | (data[pos + 2] & 0xFF);
             if (attrLen < 3 || pos + attrLen > end) {
                 pos++;
                 continue;
             }
-            if (attrType == DDM_HDR_LRECL && attrLen >= 5) {
-                hostLrecl = ((data[pos + 3] & 0xFF) << 8) | (data[pos + 4] & 0xFF);
-            } else if (attrType == DDM_HDR_RECFM && attrLen >= 4) {
-                int r = data[pos + 3] & 0xFF;
-                hostRecfm = (r == 1) ? "F" : (r == 2 ? "V" : "U");
-            } else if (attrType == DDM_HDR_BLKSIZE && attrLen >= 5) {
-                hostBlksize = ((data[pos + 3] & 0xFF) << 8) | (data[pos + 4] & 0xFF);
-            } else if (attrType == DDM_HDR_FILESIZE && attrLen >= 7) {
-                estimatedTotalBytes = (((long)(data[pos + 3] & 0xFF)) << 24) |
-                                      (((long)(data[pos + 4] & 0xFF)) << 16) |
-                                      (((long)(data[pos + 5] & 0xFF)) << 8) |
-                                      ((long)(data[pos + 6] & 0xFF));
+            switch (attrId) {
+                case DDM_HDR_LRECL:
+                    if (attrLen >= 5) {
+                        hostLrecl = ((data[pos + 3] & 0xFF) << 8) | (data[pos + 4] & 0xFF);
+                    }
+                    break;
+                case DDM_HDR_RECFM:
+                    if (attrLen >= 4) {
+                        int r = data[pos + 3] & 0xFF;
+                        if (r == 1 || r == 'F' || r == 0xC6) hostRecfm = "F";
+                        else if (r == 2 || r == 'V' || r == 0xE5) hostRecfm = "V";
+                        else if (r == 3 || r == 'U' || r == 0xE4) hostRecfm = "U";
+                    }
+                    break;
+                case DDM_HDR_BLKSIZE:
+                    if (attrLen >= 5) {
+                        hostBlksize = ((data[pos + 3] & 0xFF) << 8) | (data[pos + 4] & 0xFF);
+                    }
+                    break;
+                case DDM_HDR_FILESIZE:
+                    if (attrLen >= 7) {
+                        estimatedTotalBytes = ((long) (data[pos + 3] & 0xFF) << 24) |
+                                              ((long) (data[pos + 4] & 0xFF) << 16) |
+                                              ((long) (data[pos + 5] & 0xFF) << 8) |
+                                              (data[pos + 6] & 0xFF);
+                    }
+                    break;
+                default:
+                    break;
             }
             pos += attrLen;
         }
@@ -514,7 +542,7 @@ public class FTDft {
         log.info("DFT host message: " + msg);
 
         String msgUpper = msg.toUpperCase();
-        if (msgUpper.startsWith(END_TRANSFER) || msgUpper.contains("COMPLETE") || msgUpper.contains("TRANSFERRED") || msgUpper.contains("SUCCESS") || msgUpper.contains("DFH0500") || msgUpper.contains("DFH0501")) {
+        if (msgUpper.startsWith(END_TRANSFER) || msgUpper.startsWith("TRANS04") || msgUpper.contains("COMPLETE") || msgUpper.contains("TRANSFERRED") || msgUpper.contains("SUCCESS") || msgUpper.contains("DFH0500") || msgUpper.contains("DFH0501")) {
             listener.onTransferComplete(null);
         } else if (msgUpper.startsWith("TRANS") || msgUpper.startsWith("DFH") || msgUpper.contains("ERROR") || msgUpper.contains("FAILED") || msgUpper.contains("ABORT") || msgUpper.contains("NOT FOUND") || (listener != null && listener.getCurrentState() == FTState.ABORT_SENT)) {
             listener.onTransferAborted(msg.isEmpty() ? "Transfer aborted" : msg);
@@ -525,8 +553,8 @@ public class FTDft {
     }
 
     /**
-     * Write download data to the local file, handling ASCII conversion, RECFM F/V formatting, and EOF stripping.
-     * Conforms to IBM Host On-Demand specification.
+     * Write download data to the local file, handling ASCII conversion and EOF stripping.
+     * Conforms to x3270 / IBM Host On-Demand specification.
      */
     private void writeDownloadData(byte[] data, int offset, int length,
                                    FTConfig config) throws IOException {
@@ -542,68 +570,7 @@ public class FTDft {
             return;
         }
 
-        boolean isRecfmV = (config != null && config.getRecfm() == FTConfig.RecordFormat.VARIABLE) ||
-                           "V".equalsIgnoreCase(hostRecfm);
-        boolean isRecfmF = (config != null && config.getRecfm() == FTConfig.RecordFormat.FIXED) ||
-                           "F".equalsIgnoreCase(hostRecfm);
-        int lrecl = (config != null && config.getLrecl() > 0) ? config.getLrecl() : hostLrecl;
-
-        if (isRecfmV) {
-            downloadRecordBuffer.write(data, offset, length);
-            processVariableDownloadRecords(config);
-        } else if (isRecfmF && lrecl > 0) {
-            downloadRecordBuffer.write(data, offset, length);
-            processFixedDownloadRecords(lrecl, config);
-        } else {
-            writeConvertedChunk(data, offset, length, config);
-        }
-    }
-
-    private void processVariableDownloadRecords(FTConfig config) throws IOException {
-        while (downloadRecordBuffer.size() >= 4) {
-            byte[] buf = downloadRecordBuffer.toByteArray();
-            int rdwLen = ((buf[0] & 0xFF) << 8) | (buf[1] & 0xFF);
-            if (rdwLen < 4) {
-                downloadRecordBuffer.reset();
-                if (buf.length > 1) {
-                    downloadRecordBuffer.write(buf, 1, buf.length - 1);
-                }
-                continue;
-            }
-            if (buf.length < rdwLen) {
-                break;
-            }
-            int recDataLen = rdwLen - 4;
-            writeConvertedChunk(buf, 4, recDataLen, config);
-            outputStream.write(System.lineSeparator().getBytes(StandardCharsets.UTF_8));
-
-            downloadRecordBuffer.reset();
-            if (buf.length > rdwLen) {
-                downloadRecordBuffer.write(buf, rdwLen, buf.length - rdwLen);
-            }
-        }
-    }
-
-    private void processFixedDownloadRecords(int lrecl, FTConfig config) throws IOException {
-        while (downloadRecordBuffer.size() >= lrecl) {
-            byte[] buf = downloadRecordBuffer.toByteArray();
-            int end = lrecl;
-            while (end > 0) {
-                int b = buf[end - 1] & 0xFF;
-                if (b == 0x20 || b == 0x40 || (config != null && config.isRemapFlag() && b == FT2ASC[0x40])) {
-                    end--;
-                } else {
-                    break;
-                }
-            }
-            writeConvertedChunk(buf, 0, end, config);
-            outputStream.write(System.lineSeparator().getBytes(StandardCharsets.UTF_8));
-
-            downloadRecordBuffer.reset();
-            if (buf.length > lrecl) {
-                downloadRecordBuffer.write(buf, lrecl, buf.length - lrecl);
-            }
-        }
+        writeConvertedChunk(data, offset, length, config);
     }
 
     private void flushRemainingDownloadRecords() throws IOException {
@@ -681,45 +648,36 @@ public class FTDft {
 
         int bufferSize = getMTUSize();
         int numbytes = bufferSize - 27;
+        if (openRecsz > 0 && openRecsz < numbytes) {
+            numbytes = openRecsz;
+        }
         byte[] readBuf = new byte[numbytes];
         int totalRead = 0;
 
-        boolean isRecfmF = (config != null && config.getRecfm() == FTConfig.RecordFormat.FIXED) ||
-                           "F".equalsIgnoreCase(hostRecfm);
-        boolean isRecfmV = (config != null && config.getRecfm() == FTConfig.RecordFormat.VARIABLE) ||
-                           "V".equalsIgnoreCase(hostRecfm);
-        int lrecl = (config != null && config.getLrecl() > 0) ? config.getLrecl() : hostLrecl;
-
         try {
-            if (config != null && config.isAscii() && isRecfmF && lrecl > 0) {
-                totalRead = readFixedRecordUpload(readBuf, numbytes, lrecl, config);
-            } else if (config != null && config.isAscii() && isRecfmV) {
-                totalRead = readVariableRecordUpload(readBuf, numbytes, config);
-            } else {
-                while (!dftEof && totalRead < numbytes) {
-                    if (config != null && config.isUnicode() && inputStream instanceof haus.nightmare.lib3270j.xfer.XferFileInputUnicode) {
-                        int n = ((haus.nightmare.lib3270j.xfer.XferFileInputUnicode) inputStream).readData(readBuf, totalRead, numbytes - totalRead);
-                        if (n <= 0) {
-                            dftEof = true;
-                            break;
-                        }
-                        totalRead += n;
-                    } else if (config != null && config.isAscii()) {
-                        int b = dftAsciiRead(config);
-                        if (b == -1) {
-                            dftEof = true;
-                            break;
-                        }
-                        readBuf[totalRead++] = (byte) b;
-                    } else {
-                        if (inputStream == null) { dftEof = true; break; }
-                        int n = inputStream.read(readBuf, totalRead, numbytes - totalRead);
-                        if (n <= 0) {
-                            dftEof = true;
-                            break;
-                        }
-                        totalRead += n;
+            while (!dftEof && totalRead < numbytes) {
+                if (config != null && config.isUnicode() && inputStream instanceof haus.nightmare.lib3270j.xfer.XferFileInputUnicode) {
+                    int n = ((haus.nightmare.lib3270j.xfer.XferFileInputUnicode) inputStream).readData(readBuf, totalRead, numbytes - totalRead);
+                    if (n <= 0) {
+                        dftEof = true;
+                        break;
                     }
+                    totalRead += n;
+                } else if (config != null && config.isAscii()) {
+                    int b = dftAsciiRead(config);
+                    if (b == -1) {
+                        dftEof = true;
+                        break;
+                    }
+                    readBuf[totalRead++] = (byte) b;
+                } else {
+                    if (inputStream == null) { dftEof = true; break; }
+                    int n = inputStream.read(readBuf, totalRead, numbytes - totalRead);
+                    if (n <= 0) {
+                        dftEof = true;
+                        break;
+                    }
+                    totalRead += n;
                 }
             }
         } catch (IOException e) {
@@ -781,147 +739,6 @@ public class FTDft {
         }
     }
 
-    private byte[] readNextUploadLineConverted(FTConfig config) throws IOException {
-        if (inputStream == null || dftEof) return null;
-        ByteArrayOutputStream lineBytes = new ByteArrayOutputStream();
-        int c;
-        boolean hasData = false;
-        while ((c = inputStream.read()) != -1) {
-            hasData = true;
-            if (c == '\r') {
-                continue; // ignore CR
-            }
-            if (c == '\n') {
-                break;
-            }
-            if (c == EOF_CTRL_Z || c == EOF_CTRL_D) {
-                break;
-            }
-            lineBytes.write(c);
-        }
-        if (!hasData && c == -1) {
-            return null;
-        }
-
-        byte[] raw = lineBytes.toByteArray();
-        return convertLineForUpload(raw, config);
-    }
-
-    private byte[] convertLineForUpload(byte[] raw, FTConfig config) {
-        String lineStr = new String(raw, StandardCharsets.UTF_8);
-        ByteArrayOutputStream converted = new ByteArrayOutputStream(raw.length + 8);
-        boolean isDbcs = (config != null && config.isDbcs()) || (translator != null && translator.getCodePage() != null && translator.getCodePage().isDBCS());
-        boolean noSo = config != null && config.isOptionNoso();
-        boolean inDbcsState = false;
-
-        for (int i = 0; i < lineStr.length(); i++) {
-            char ch = lineStr.charAt(i);
-            int dbcsVal = (isDbcs && translator != null) ? translator.unicodeToDbcs(ch) : -1;
-            if (dbcsVal != -1) {
-                if (!inDbcsState && !noSo) {
-                    converted.write(0x0E); // Shift-Out
-                    inDbcsState = true;
-                }
-                converted.write((dbcsVal >> 8) & 0xFF);
-                converted.write(dbcsVal & 0xFF);
-            } else {
-                if (inDbcsState && !noSo) {
-                    converted.write(0x0F); // Shift-In
-                    inDbcsState = false;
-                }
-                converted.write(convertAsciiByte(ch, config));
-            }
-        }
-        if (inDbcsState && !noSo) {
-            converted.write(0x0F); // Shift-In at end of record
-        }
-        return converted.toByteArray();
-    }
-
-    private int readFixedRecordUpload(byte[] outBuf, int maxBytes, int lrecl, FTConfig config) throws IOException {
-        int totalRead = 0;
-        int padByte = (config != null && config.isRemapFlag()) ? FT2ASC[0x40] : 0x20;
-
-        while (totalRead + lrecl <= maxBytes && !dftEof) {
-            byte[] rec;
-            if (pendingUploadRecord != null) {
-                rec = pendingUploadRecord;
-                pendingUploadRecord = null;
-            } else {
-                rec = readNextUploadLineConverted(config);
-                if (rec == null) {
-                    dftEof = true;
-                    break;
-                }
-            }
-
-            if (rec.length <= lrecl) {
-                System.arraycopy(rec, 0, outBuf, totalRead, rec.length);
-                totalRead += rec.length;
-                int padCount = lrecl - rec.length;
-                for (int p = 0; p < padCount; p++) {
-                    outBuf[totalRead++] = (byte) padByte;
-                }
-            } else {
-                // Longer than lrecl: split
-                System.arraycopy(rec, 0, outBuf, totalRead, lrecl);
-                totalRead += lrecl;
-                int rem = rec.length - lrecl;
-                pendingUploadRecord = new byte[rem];
-                System.arraycopy(rec, lrecl, pendingUploadRecord, 0, rem);
-            }
-        }
-        return totalRead;
-    }
-
-    private int readVariableRecordUpload(byte[] outBuf, int maxBytes, FTConfig config) throws IOException {
-        int totalRead = 0;
-        while (totalRead + 4 < maxBytes && !dftEof) {
-            byte[] rec;
-            if (pendingUploadRecord != null) {
-                rec = pendingUploadRecord;
-                pendingUploadRecord = null;
-            } else {
-                rec = readNextUploadLineConverted(config);
-                if (rec == null) {
-                    dftEof = true;
-                    break;
-                }
-            }
-
-            int needed = rec.length + 4;
-            if (totalRead + needed <= maxBytes) {
-                outBuf[totalRead++] = (byte) ((needed >> 8) & 0xFF);
-                outBuf[totalRead++] = (byte) (needed & 0xFF);
-                outBuf[totalRead++] = 0;
-                outBuf[totalRead++] = 0;
-                System.arraycopy(rec, 0, outBuf, totalRead, rec.length);
-                totalRead += rec.length;
-            } else {
-                if (totalRead > 0) {
-                    // Save for next MTU buffer
-                    pendingUploadRecord = rec;
-                    break;
-                } else {
-                    // Single record exceeds entire MTU: split
-                    int chunk = maxBytes - 4;
-                    int rdwLen = chunk + 4;
-                    outBuf[totalRead++] = (byte) ((rdwLen >> 8) & 0xFF);
-                    outBuf[totalRead++] = (byte) (rdwLen & 0xFF);
-                    outBuf[totalRead++] = 0;
-                    outBuf[totalRead++] = 0;
-                    System.arraycopy(rec, 0, outBuf, totalRead, chunk);
-                    totalRead += chunk;
-                    int rem = rec.length - chunk;
-                    pendingUploadRecord = new byte[rem];
-                    System.arraycopy(rec, chunk, pendingUploadRecord, 0, rem);
-                    break;
-                }
-            }
-        }
-        return totalRead;
-    }
-
     /**
      * Explicitly send a framed data packet buffer to the host using DFT structured fields.
      * Supports CICS, TSO, and VM/CMS data packaging.
@@ -987,6 +804,16 @@ public class FTDft {
         }
     }
 
+    private int readRawByte() throws IOException {
+        if (lookaheadByte != -1) {
+            int b = lookaheadByte;
+            lookaheadByte = -1;
+            return b;
+        }
+        if (inputStream == null) return -1;
+        return inputStream.read();
+    }
+
     /**
      * Read a byte from local file for upload, handling ASCII conversion and remapping.
      * Matching x3270 dft_ascii_read logic.
@@ -998,26 +825,39 @@ public class FTDft {
             return b;
         }
 
-        if (inputStream == null) return -1;
-
-        int c = inputStream.read();
+        int c = readRawByte();
         if (c == -1) return -1;
 
-        if (config.isCrFlag() && !lastCr && c == '\n') {
-            lastCr = false;
-            // Expand \n to \r\n: buffer \n in pendingByte, return \r now
-            pendingByte = convertAsciiByte('\n', config);
-            return convertAsciiByte('\r', config);
+        if (config.isCrFlag()) {
+            if (c == '\r') {
+                int next = readRawByte();
+                while (next == '\r') {
+                    next = readRawByte();
+                }
+                if (next != '\n' && next != -1) {
+                    lookaheadByte = next;
+                }
+                pendingByte = convertAsciiByte('\n', config);
+                return convertAsciiByte('\r', config);
+            } else if (c == '\n') {
+                int next = readRawByte();
+                while (next == '\r') {
+                    next = readRawByte();
+                }
+                if (next != -1) {
+                    lookaheadByte = next;
+                }
+                pendingByte = convertAsciiByte('\n', config);
+                return convertAsciiByte('\r', config);
+            }
         }
-        lastCr = (c == '\r');
 
         return convertAsciiByte((char) c, config);
     }
 
     private int convertAsciiByte(char c, FTConfig config) {
         if (!config.isRemapFlag()) {
-            int ebc = translator.unicodeToEbcdic(c);
-            return ebc >= 0 ? ebc : 0x40;
+            return c & 0xFF;
         }
 
         /*
@@ -1025,7 +865,7 @@ public class FTDft {
          * Translate Unicode char c -> EBCDIC -> host pseudo-ASCII FT2ASC[ebc].
          */
         int ebc;
-        if (c < 0x20 || (c >= 0x80 && c < 0x9F)) {
+        if (c < 0x20 || c == 0x7F || (c >= 0x80 && c < 0x9F)) {
             ebc = ASC2FT[c & 0xFF];
         } else if (c == 0x9F) {
             ebc = 0xFF;
@@ -1050,9 +890,13 @@ public class FTDft {
 
         input.sendStructuredFieldData(RB_CLOSE_ACK.clone());
 
-        if (listener.getCurrentState() != FTState.NONE) {
-            log.info("DFT: File transfer completed on close request (" + bytesTransferred + " bytes)");
-            listener.onTransferComplete(null);
+        if (messageFlag || !dataStreamOpened) {
+            if (listener != null && listener.getCurrentState() != FTState.NONE) {
+                log.info("DFT: File transfer completed on close (" + bytesTransferred + " bytes)");
+                listener.onTransferComplete(null);
+            }
+        } else {
+            dataStreamOpened = false;
         }
     }
 
@@ -1062,13 +906,24 @@ public class FTDft {
         input.sendStructuredFieldData(createDataAck(recnum++));
     }
 
+    private void sendOpenFailed() {
+        if (RB_OPEN_FAILED.length > 0 && (RB_OPEN_FAILED[0] & 0xFF) == AID_SF) {
+            input.sendStructuredFieldData(RB_OPEN_FAILED.clone());
+        } else {
+            byte[] pkt = new byte[RB_OPEN_FAILED.length + 1];
+            pkt[0] = (byte) AID_SF;
+            System.arraycopy(RB_OPEN_FAILED, 0, pkt, 1, RB_OPEN_FAILED.length);
+            input.sendStructuredFieldData(pkt);
+        }
+    }
+
     // ========== Abort ==========
 
     private void dftAbort(String message, int code) {
         log.warning("DFT: ABORT — " + message);
 
         if (code == TR_OPEN_REQ) {
-            input.sendStructuredFieldData(RB_OPEN_FAILED.clone());
+            sendOpenFailed();
         } else {
             ByteArrayOutputStream out = new ByteArrayOutputStream(10);
             out.write(AID_SF);

lib3270j/src/main/java/haus/nightmare/lib3270j/input/InputProcessor.java

@@ -1977,8 +1977,15 @@ public class InputProcessor {
     public void sendAidForFT(int aidCode) {
         boolean wasLocked = keyboardLocked;
         keyboardLocked = false;
-        sendAid(aidCode);
-        keyboardLocked = wasLocked;
+        int prevInhibit = (oia != null) ? oia.getInputInhibited() : ECLConstants.INHIBIT_NOT_INHIBITED;
+        if (oia != null) {
+            oia.setInputInhibited(ECLConstants.INHIBIT_NOT_INHIBITED);
+        }
+        try {
+            sendAid(aidCode);
+        } finally {
+            keyboardLocked = wasLocked;
+        }
     }
 
     /**
@@ -2039,11 +2046,11 @@ public class InputProcessor {
         // Find the field at cursor and erase it
         int curAddr = screen.getCursorAddress();
         byte faVal = screen.getFieldAttributeAt(curAddr);
-        if (faIsProtected(faVal & 0xFF)) {
+        if (screen.getCell(curAddr).isFieldAttribute() || faIsProtected(faVal & 0xFF)) {
             // Try to find first unprotected field
             curAddr = screen.findNextUnprotected(curAddr);
             faVal = screen.getFieldAttributeAt(curAddr);
-            if (faIsProtected(faVal & 0xFF)) {
+            if (screen.getCell(curAddr).isFieldAttribute() || faIsProtected(faVal & 0xFF)) {
                 return -3; // No unprotected field
             }
         }
@@ -2517,6 +2524,8 @@ public class InputProcessor {
     public void sendStructuredFieldData(byte[] data) {
         if (fsm != null) {
             fsm.send3270Data(data);
+        } else if (outputSender != null) {
+            outputSender.send3270Data(data);
         }
     }
 

lib3270j/src/main/java/haus/nightmare/lib3270j/nvt/NvtProcessor.java

@@ -38,6 +38,7 @@ public class NvtProcessor {
     private static final int STATE_OSC      = 4;
     private static final int STATE_OSC_ESC  = 5;
 
+    private static final int MAX_ESC_BUFFER_SIZE = 4096;
     private int parseState = STATE_NORMAL;
     private final ByteArrayOutputStream escBuffer = new ByteArrayOutputStream();
 
@@ -470,32 +471,51 @@ public class NvtProcessor {
             } else if (parseState == STATE_OSC) {
                 if (b == 0x07) { // BEL terminator
                     handleOSC(escBuffer.toByteArray());
+                    escBuffer.reset();
                     parseState = STATE_NORMAL;
                 } else if (b == 0x1B) { // Possible ESC \ (ST)
                     parseState = STATE_OSC_ESC;
                 } else if (b == 0x9C) { // 8-bit ST
                     handleOSC(escBuffer.toByteArray());
+                    escBuffer.reset();
                     parseState = STATE_NORMAL;
                 } else {
-                    escBuffer.write(b);
+                    if (escBuffer.size() < MAX_ESC_BUFFER_SIZE) {
+                        escBuffer.write(b);
+                    } else {
+                        escBuffer.reset();
+                        parseState = STATE_NORMAL;
+                    }
                 }
             } else if (parseState == STATE_OSC_ESC) {
                 if (b == '\\') { // ESC \ (ST) terminator
                     handleOSC(escBuffer.toByteArray());
+                    escBuffer.reset();
                     parseState = STATE_NORMAL;
                 } else {
                     // False alarm on ST, put ESC and byte into OSC buffer
-                    escBuffer.write(0x1B);
-                    escBuffer.write(b);
-                    parseState = STATE_OSC;
+                    if (escBuffer.size() + 2 <= MAX_ESC_BUFFER_SIZE) {
+                        escBuffer.write(0x1B);
+                        escBuffer.write(b);
+                        parseState = STATE_OSC;
+                    } else {
+                        escBuffer.reset();
+                        parseState = STATE_NORMAL;
+                    }
                 }
             } else if (parseState == STATE_CSI) {
-                escBuffer.write(b);
+                if (escBuffer.size() < MAX_ESC_BUFFER_SIZE) {
+                    escBuffer.write(b);
+                }
                 // CSI final bytes are in the range 0x40..0x7E
                 if (b >= 0x40 && b <= 0x7E) {
                     byte[] seq = escBuffer.toByteArray();
+                    escBuffer.reset();
                     curAddr = processAnsiEscapeSequence(seq, curAddr, rows, cols);
                     parseState = STATE_NORMAL;
+                } else if (escBuffer.size() >= MAX_ESC_BUFFER_SIZE) {
+                    escBuffer.reset();
+                    parseState = STATE_NORMAL;
                 }
             }
         }

lib3270j/src/main/java/haus/nightmare/lib3270j/printer/PD3270.java

@@ -24,6 +24,9 @@ public class PD3270 {
     private String destination;
     private boolean open = false;
 
+    /** Maximum size of in-memory print capture buffer (1 MB) to prevent unbounded heap growth. */
+    public static final int MAX_MEMORY_CAPTURE_SIZE = 1048576;
+
     private OutputStream targetOutputStream;
     private Writer targetWriter;
     private Process pipeProcess;
@@ -33,6 +36,13 @@ public class PD3270 {
     private int pageCount = 0;
     private Charset outputCharset = StandardCharsets.UTF_8;
 
+    private void appendToMemoryStream(byte[] data, int offset, int length) {
+        int remaining = MAX_MEMORY_CAPTURE_SIZE - memoryStream.size();
+        if (remaining > 0) {
+            memoryStream.write(data, offset, Math.min(length, remaining));
+        }
+    }
+
     public PD3270() {
         this(new PrinterConfig());
     }
@@ -102,7 +112,7 @@ public class PD3270 {
         }
 
         try {
-            memoryStream.write(data, offset, length);
+            appendToMemoryStream(data, offset, length);
             byteCount += length;
 
             if (targetOutputStream != null) {
@@ -129,7 +139,7 @@ public class PD3270 {
         }
         try {
             byte[] b = String.valueOf(c).getBytes(outputCharset);
-            memoryStream.write(b);
+            appendToMemoryStream(b, 0, b.length);
             byteCount += b.length;
 
             if (targetWriter != null) {
@@ -158,7 +168,7 @@ public class PD3270 {
         }
         try {
             byte[] b = s.getBytes(outputCharset);
-            memoryStream.write(b);
+            appendToMemoryStream(b, 0, b.length);
             byteCount += b.length;
 
             if (targetWriter != null) {

lib3270j/src/main/java/haus/nightmare/lib3270j/printer/PrinterConfig.java

@@ -54,6 +54,8 @@ public class PrinterConfig {
     private long autoFlushTimeoutMs = 2000;
     private int graphicErrorAction = PrinterConstants.GEA_NO_SUBSTITUTION;
     private char graphicErrorReplacementChar = '?';
+    public static final int DEFAULT_MAX_FRAMING_BUFFER_SIZE = 131072; // 128KB
+    private int maxFramingBufferSize = DEFAULT_MAX_FRAMING_BUFFER_SIZE;
 
     public PrinterConfig() {
         initDefaultChannelTable();
@@ -227,4 +229,9 @@ public class PrinterConfig {
     public int[] getChannelTable() {
         return channelTable.clone();
     }
+
+    public int getMaxFramingBufferSize() { return maxFramingBufferSize; }
+    public void setMaxFramingBufferSize(int maxFramingBufferSize) {
+        this.maxFramingBufferSize = maxFramingBufferSize > 0 ? maxFramingBufferSize : DEFAULT_MAX_FRAMING_BUFFER_SIZE;
+    }
 }

lib3270j/src/main/java/haus/nightmare/lib3270j/printer/Telnet3270EP.java

@@ -58,12 +58,19 @@ public class Telnet3270EP implements Runnable {
     private int lastResponseRequired = TN3270EConstants.RSF_NO_RESPONSE;
 
     // Buffer for Telnet streaming
-    private final ByteArrayOutputStream recordBuffer = new ByteArrayOutputStream();
+    private static final int MAX_PRINTER_SUBNEG_SIZE = 8192;
+    private final int maxFramingBufferSize;
+    private boolean recordDiscardMode = false;
+    private boolean subnegDiscardMode = false;
+    private final haus.nightmare.lib3270j.datastream.FastByteBuffer recordBuffer;
     private final ByteArrayOutputStream subnegBuffer = new ByteArrayOutputStream();
     private boolean inSubnegotiation = false;
 
     public Telnet3270EP(PrinterConfig config) {
         this.config = config != null ? config : new PrinterConfig();
+        this.maxFramingBufferSize = this.config.getMaxFramingBufferSize();
+        this.recordBuffer = new haus.nightmare.lib3270j.datastream.FastByteBuffer(
+                Math.min(32768, this.maxFramingBufferSize), this.maxFramingBufferSize);
         this.pd = new PD3270(this.config);
         this.translator = new EbcdicTranslator(this.config.getCodePage());
         this.scs = new PrintSCS3270(this.config, this.pd, this.translator);
@@ -73,6 +80,9 @@ public class Telnet3270EP implements Runnable {
 
     public Telnet3270EP(PrinterConfig config, PD3270 pd, EbcdicTranslator translator) {
         this.config = config != null ? config : new PrinterConfig();
+        this.maxFramingBufferSize = this.config.getMaxFramingBufferSize();
+        this.recordBuffer = new haus.nightmare.lib3270j.datastream.FastByteBuffer(
+                Math.min(32768, this.maxFramingBufferSize), this.maxFramingBufferSize);
         this.pd = pd != null ? pd : new PD3270(this.config);
         this.translator = translator != null ? translator : new EbcdicTranslator(this.config.getCodePage());
         this.scs = new PrintSCS3270(this.config, this.pd, this.translator);
@@ -191,6 +201,7 @@ public class Telnet3270EP implements Runnable {
         this.recordBuffer.reset();
         this.subnegBuffer.reset();
         this.inSubnegotiation = false;
+        this.recordDiscardMode = false;
 
         scs.resetSCSFormatDefaults();
         printPs.erasePrintBuffer();
@@ -376,14 +387,31 @@ public class Telnet3270EP implements Runnable {
                     if (idx < end && (data[idx] & 0xFF) == TelnetConstants.SE) {
                         idx++;
                         inSubnegotiation = false;
-                        processSubnegotiation(subnegBuffer.toByteArray());
+                        if (!subnegDiscardMode) {
+                            processSubnegotiation(subnegBuffer.toByteArray());
+                        }
                         subnegBuffer.reset();
+                        subnegDiscardMode = false;
                     } else if (idx < end && (data[idx] & 0xFF) == TelnetConstants.IAC) {
-                        subnegBuffer.write(TelnetConstants.IAC);
+                        if (!subnegDiscardMode) {
+                            if (subnegBuffer.size() < MAX_PRINTER_SUBNEG_SIZE) {
+                                subnegBuffer.write(TelnetConstants.IAC);
+                            } else {
+                                log.warning("Printer subnegotiation exceeded " + MAX_PRINTER_SUBNEG_SIZE + " bytes; discarding until IAC SE");
+                                subnegBuffer.reset();
+                                subnegDiscardMode = true;
+                            }
+                        }
                         idx++;
                     }
-                } else {
-                    subnegBuffer.write(b);
+                } else if (!subnegDiscardMode) {
+                    if (subnegBuffer.size() < MAX_PRINTER_SUBNEG_SIZE) {
+                        subnegBuffer.write(b);
+                    } else {
+                        log.warning("Printer subnegotiation exceeded " + MAX_PRINTER_SUBNEG_SIZE + " bytes; discarding until IAC SE");
+                        subnegBuffer.reset();
+                        subnegDiscardMode = true;
+                    }
                 }
                 continue;
             }
@@ -394,15 +422,19 @@ public class Telnet3270EP implements Runnable {
 
                 switch (cmd) {
                     case TelnetConstants.IAC:
-                        recordBuffer.write(TelnetConstants.IAC);
+                        appendPrinterByte(TelnetConstants.IAC);
                         break;
                     case TelnetConstants.SB:
                         inSubnegotiation = true;
+                        subnegDiscardMode = false;
                         subnegBuffer.reset();
                         break;
                     case TelnetConstants.EOR:
-                        processCompleteRecord(recordBuffer.toByteArray());
+                        if (!recordDiscardMode) {
+                            processCompleteRecord(recordBuffer.toByteArray());
+                        }
                         recordBuffer.reset();
+                        recordDiscardMode = false;
                         break;
                     case TelnetConstants.DO:
                         if (idx < end) handleTelnetDo(data[idx++] & 0xFF);
@@ -420,11 +452,33 @@ public class Telnet3270EP implements Runnable {
                         break;
                 }
             } else {
-                recordBuffer.write(b);
+                appendPrinterByte(b);
             }
         }
     }
 
+    private void appendPrinterByte(int b) {
+        if (recordDiscardMode) {
+            return;
+        }
+        if (recordBuffer.size() >= maxFramingBufferSize) {
+            log.warning("Printer record buffer exceeded maximum capacity (" + maxFramingBufferSize +
+                    " bytes) without IAC EOR; discarding until next EOR");
+            recordDiscardMode = true;
+            recordBuffer.reset();
+            return;
+        }
+        recordBuffer.write(b);
+    }
+
+    public boolean isRecordDiscardMode() {
+        return recordDiscardMode;
+    }
+
+    public int getMaxFramingBufferSize() {
+        return maxFramingBufferSize;
+    }
+
     private void handleTelnetDo(int option) {
         try {
             if (option == TelnetConstants.TELOPT_TN3270E) {

lib3270j/src/main/java/haus/nightmare/lib3270j/telnet/TelnetFSM.java

@@ -46,8 +46,15 @@ public class TelnetFSM {
     private final boolean[] myOpts  = new boolean[256]; // options we have enabled
     private final boolean[] hisOpts = new boolean[256]; // options the host has enabled
 
-    // 3270 input buffer (accumulated between telnet framing)
-    private final haus.nightmare.lib3270j.datastream.FastByteBuffer ibuf = new haus.nightmare.lib3270j.datastream.FastByteBuffer(32768);
+    // 3270 input buffer (accumulated between telnet framing, bounded at maxFramingBufferSize)
+    private final haus.nightmare.lib3270j.datastream.FastByteBuffer ibuf;
+
+    // Discard mode if framing buffer overflows prior to receiving IAC EOR
+    private boolean recordDiscardMode = false;
+
+    // Sanity cap for Telnet subnegotiation parameters (RFC 1091, RFC 1572, RFC 2355)
+    private static final int MAX_SUBNEG_BUFFER_SIZE = 8192;
+    private boolean sbDiscardMode = false;
 
     // Reusable single-byte scratch buffer for plain NVT data dispatch (Phase 27.5 / T1-C)
     private final byte[] nvtSingleByteScratch = new byte[1];
@@ -165,6 +172,8 @@ public class TelnetFSM {
         this.config = config;
         this.screenBuffer = screenBuffer;
         this.dsProcessor = dsProcessor;
+        int maxFraming = (config != null) ? config.getMaxFramingBufferSize() : ConnectionConfig.DEFAULT_MAX_FRAMING_BUFFER_SIZE;
+        this.ibuf = new haus.nightmare.lib3270j.datastream.FastByteBuffer(Math.min(32768, maxFraming), maxFraming);
         this.nvtProcessor = new haus.nightmare.lib3270j.nvt.NvtProcessor(screenBuffer, new haus.nightmare.lib3270j.charset.EbcdicTranslator());
         this.nvtProcessor.setOutputSender(this::sendNvtData);
     }
@@ -220,6 +229,8 @@ public class TelnetFSM {
         deferredWillTtype = false;
         ttypeIndex = 0;
         luIndex = 0;
+        recordDiscardMode = false;
+        sbDiscardMode = false;
         ibuf.reset();
         sbbuf.reset();
 
@@ -256,7 +267,7 @@ public class TelnetFSM {
                     if (isPlainNvt) {
                         nvtProcessor.processNVTData(buf, start, i - start);
                     } else if (connectionState.is3270() || connectionState.isTn3270e() || connectionState == ConnectionState.TELNET_PENDING || hisOpts[TELOPT_BINARY] || hisOpts[TELOPT_EOR]) {
-                        ibuf.write(buf, start, i - start);
+                        appendInboundData(buf, start, i - start);
                     }
                 }
                 if (i < end) {
@@ -334,24 +345,80 @@ public class TelnetFSM {
 
         // Accumulate data for 3270, TN3270E (including CONNECTED_E_NVT, SSCP-LU and unbound states, and pending)
         if (connectionState.is3270() || connectionState.isTn3270e() || connectionState == ConnectionState.TELNET_PENDING || hisOpts[TELOPT_BINARY] || hisOpts[TELOPT_EOR]) {
-            ibuf.write(c);
+            appendInboundByte(c);
         }
     }
 
+    private void appendInboundByte(int c) {
+        if (recordDiscardMode) {
+            return;
+        }
+        if (ibuf.size() >= ibuf.getMaxCapacity()) {
+            handleFramingOverflow();
+            return;
+        }
+        try {
+            ibuf.write(c);
+        } catch (haus.nightmare.lib3270j.datastream.FramingBufferOverflowException e) {
+            handleFramingOverflow();
+        }
+    }
+
+    private void appendInboundData(byte[] buf, int offset, int len) {
+        if (recordDiscardMode || buf == null || len <= 0) {
+            return;
+        }
+        if (ibuf.size() + len > ibuf.getMaxCapacity()) {
+            handleFramingOverflow();
+            return;
+        }
+        try {
+            ibuf.write(buf, offset, len);
+        } catch (haus.nightmare.lib3270j.datastream.FramingBufferOverflowException e) {
+            handleFramingOverflow();
+        }
+    }
+
+    private void handleFramingOverflow() {
+        log.warning("Inbound 3270 framing buffer exceeded maximum capacity (" + ibuf.getMaxCapacity() +
+                " bytes) without IAC EOR; discarding record until next EOR");
+        recordDiscardMode = true;
+        ibuf.reset();
+    }
+
+    public boolean isRecordDiscardMode() {
+        return recordDiscardMode;
+    }
+
+    public int getMaxFramingBufferSize() {
+        return ibuf.getMaxCapacity();
+    }
+
+    public int getCurrentFramingBufferSize() {
+        return ibuf.size();
+    }
+
     // ========== TNS_IAC ==========
 
     private void processIAC(int c) {
         switch (c) {
             case IAC: // Escaped IAC — literal 0xFF
-                ibuf.write(c);
+                if ((connectionState == ConnectionState.CONNECTED_NVT || connectionState == ConnectionState.CONNECTED_NVT_CHAR)
+                        && !(hisOpts[TELOPT_BINARY] && hisOpts[TELOPT_EOR])) {
+                    nvtSingleByteScratch[0] = (byte) c;
+                    nvtProcessor.processNVTData(nvtSingleByteScratch, 0, 1);
+                } else {
+                    appendInboundByte(c);
+                }
                 state = TNS_DATA;
                 break;
             case EOR: // End of record — process accumulated 3270 data
                 log.fine("RCVD EOR");
-                if (connectionState.is3270() || connectionState.isTn3270e() || connectionState == ConnectionState.TELNET_PENDING) {
+                if (!recordDiscardMode && (connectionState.is3270() || connectionState.isTn3270e() || connectionState == ConnectionState.TELNET_PENDING)) {
                     processEndOfRecord();
                 }
                 ibuf.reset();
+                recordDiscardMode = false;
                 state = TNS_DATA;
                 break;
             case WILL: state = TNS_WILL; break;
@@ -360,6 +427,7 @@ public class TelnetFSM {
             case DONT: state = TNS_DONT; break;
             case SB:
                 sbbuf.reset();
+                sbDiscardMode = false;
                 state = TNS_SB;
                 break;
             case GA:
@@ -514,6 +582,9 @@ public class TelnetFSM {
 
     private void processDont(int opt) {
         log.info("RCVD DONT " + TelnetConstants.optionName(opt));
+        if (opt == TELOPT_TTYPE) {
+            ttypeIndex = 0;
+        }
         if (myOpts[opt]) {
             myOpts[opt] = false;
             sendCommand(WONT, opt);
@@ -526,8 +597,15 @@ public class TelnetFSM {
     private void processSB(int c) {
         if (c == IAC) {
             state = TNS_SB_IAC;
-        } else {
-            sbbuf.write(c);
+        } else if (!sbDiscardMode) {
+            if (sbbuf.size() < MAX_SUBNEG_BUFFER_SIZE) {
+                sbbuf.write(c);
+            } else {
+                log.warning("Telnet subnegotiation exceeded " + MAX_SUBNEG_BUFFER_SIZE +
+                        " bytes without IAC SE; discarding until IAC SE");
+                sbbuf.reset();
+                sbDiscardMode = true;
+            }
         }
     }
 
@@ -536,19 +614,34 @@ public class TelnetFSM {
     private void processSBIAC(int c) {
         if (c == SE) {
             // Sub-negotiation complete
-            byte[] sbData = sbbuf.toByteArray();
-            sbbuf.reset();
-            processSubNegotiation(sbData);
+            if (!sbDiscardMode) {
+                byte[] sbData = sbbuf.toByteArray();
+                sbbuf.reset();
+                processSubNegotiation(sbData);
+            } else {
+                sbbuf.reset();
+                sbDiscardMode = false;
+            }
             state = TNS_DATA;
         } else if (c == IAC) {
             // Escaped IAC within sub-negotiation
-            sbbuf.write(IAC);
+            if (!sbDiscardMode) {
+                if (sbbuf.size() < MAX_SUBNEG_BUFFER_SIZE) {
+                    sbbuf.write(IAC);
+                } else {
+                    log.warning("Telnet subnegotiation exceeded " + MAX_SUBNEG_BUFFER_SIZE +
+                            " bytes without IAC SE; discarding until IAC SE");
+                    sbbuf.reset();
+                    sbDiscardMode = true;
+                }
+            }
             state = TNS_SB;
         } else {
-            // Shouldn't happen, but recover
+            // Unexpected command after IAC inside SB (e.g. missing SE): abort SB and process command
             log.warning("Unexpected byte " + c + " after IAC in SB");
             sbbuf.reset();
-            state = TNS_DATA;
+            sbDiscardMode = false;
+            processIAC(c);
         }
     }
 
@@ -1634,6 +1727,7 @@ public class TelnetFSM {
         state = TNS_DATA;
         java.util.Arrays.fill(myOpts, false);
         java.util.Arrays.fill(hisOpts, false);
+        recordDiscardMode = false;
         ibuf.reset();
         sbbuf.reset();
         tn3270eNegotiated = false;

lib3270j/src/test/java/haus/nightmare/lib3270j/Phase30LibraryDistributionTest.java

@@ -66,7 +66,8 @@ public class Phase30LibraryDistributionTest {
         String setupShContent = Files.readString(setupSh.toPath());
         assertTrue(setupShContent.contains("lib3270j.jar"), "setup.sh must package lib3270j.jar");
         assertTrue(setupShContent.contains("Implementation-Title: lib3270j"), "setup.sh must set Implementation-Title: lib3270j");
-        assertTrue(setupShContent.contains("Implementation-Version: 1.2.4"), "setup.sh must set Implementation-Version: 1.2.4");
+        assertTrue(setupShContent.contains("Implementation-Version: " + Version.VERSION),
+                "setup.sh must set Implementation-Version: " + Version.VERSION);
 
         // 3. setup.ps1
         File setupPs1 = new File(projectRoot, "setup.ps1");
@@ -74,7 +75,8 @@ public class Phase30LibraryDistributionTest {
         String setupPs1Content = Files.readString(setupPs1.toPath());
         assertTrue(setupPs1Content.contains("lib3270j.jar"), "setup.ps1 must package lib3270j.jar");
         assertTrue(setupPs1Content.contains("Implementation-Title: lib3270j"), "setup.ps1 must set Implementation-Title: lib3270j");
-        assertTrue(setupPs1Content.contains("Implementation-Version: 1.2.4"), "setup.ps1 must set Implementation-Version: 1.2.4");
+        assertTrue(setupPs1Content.contains("Implementation-Version: " + Version.VERSION),
+                "setup.ps1 must set Implementation-Version: " + Version.VERSION);
     }
 
     @Test
@@ -112,12 +114,13 @@ public class Phase30LibraryDistributionTest {
     @DisplayName("Phase 30.2: Maven local published artifacts exist and validate if maven-publish was executed")
     public void testMavenLocalPublishedArtifacts() throws Exception {
         String userHome = System.getProperty("user.home");
-        File m2ArtifactDir = new File(userHome, ".m2/repository/haus/nightmare/j3270/lib3270j/1.2.4");
+        String version = Version.VERSION;
+        File m2ArtifactDir = new File(userHome, ".m2/repository/haus/nightmare/j3270/lib3270j/" + version);
         if (m2ArtifactDir.exists()) {
-            File pomFile = new File(m2ArtifactDir, "lib3270j-1.2.4.pom");
-            File jarFile = new File(m2ArtifactDir, "lib3270j-1.2.4.jar");
-            File sourcesFile = new File(m2ArtifactDir, "lib3270j-1.2.4-sources.jar");
-            File javadocFile = new File(m2ArtifactDir, "lib3270j-1.2.4-javadoc.jar");
+            File pomFile = new File(m2ArtifactDir, "lib3270j-" + version + ".pom");
+            File jarFile = new File(m2ArtifactDir, "lib3270j-" + version + ".jar");
+            File sourcesFile = new File(m2ArtifactDir, "lib3270j-" + version + "-sources.jar");
+            File javadocFile = new File(m2ArtifactDir, "lib3270j-" + version + "-javadoc.jar");
 
             assertTrue(pomFile.exists() && pomFile.length() > 0, "POM file must exist and be non-empty");
             assertTrue(jarFile.exists() && jarFile.length() > 0, "JAR file must exist and be non-empty");
@@ -127,7 +130,7 @@ public class Phase30LibraryDistributionTest {
             String pomXml = Files.readString(pomFile.toPath());
             assertTrue(pomXml.contains("<groupId>haus.nightmare.j3270</groupId>"), "POM must contain groupId");
             assertTrue(pomXml.contains("<artifactId>lib3270j</artifactId>"), "POM must contain artifactId");
-            assertTrue(pomXml.contains("<version>1.2.4</version>"), "POM must contain version 1.2.4");
+            assertTrue(pomXml.contains("<version>" + version + "</version>"), "POM must contain version " + version);
             assertTrue(pomXml.contains("The Unlicense"), "POM must contain Unlicense");
             assertFalse(pomXml.contains("Apache"), "lib3270j POM must not contain Apache license");
             assertFalse(pomXml.contains("<dependencies>"), "lib3270j POM must have zero external dependencies");

lib3270j/src/test/java/haus/nightmare/lib3270j/datastream/FastByteBufferTest.java

@@ -151,4 +151,40 @@ public class FastByteBufferTest {
         executor.shutdown();
         assertEquals(0, failures.get(), "No failures occurred during concurrent pool operations");
     }
+
+    @Test
+    @DisplayName("FastByteBuffer enforces maxCapacity and throws FramingBufferOverflowException")
+    public void testFastByteBufferMaxCapacityEnforcement() {
+        FastByteBuffer buf = new FastByteBuffer(64, 128);
+        assertEquals(128, buf.getMaxCapacity());
+        assertEquals(64, buf.getInitialCapacity());
+
+        byte[] chunk = new byte[64];
+        buf.write(chunk, 0, 64);
+        assertEquals(64, buf.size());
+
+        buf.write(chunk, 0, 64);
+        assertEquals(128, buf.size());
+        assertEquals(128, buf.buffer().length);
+
+        // Writing one more byte must throw FramingBufferOverflowException
+        assertThrows(FramingBufferOverflowException.class, () -> buf.write(0xFF));
+
+        // Writing a chunk that exceeds capacity must also throw
+        assertThrows(FramingBufferOverflowException.class, () -> buf.write(chunk, 0, 10));
+
+        // After reset, buffer is ready for use again
+        buf.reset();
+        assertEquals(0, buf.size());
+        buf.write(chunk, 0, 64);
+        assertEquals(64, buf.size());
+    }
+
+    @Test
+    @DisplayName("FastByteBuffer default maxCapacity is 131072 bytes (128KB)")
+    public void testDefaultMaxCapacity() {
+        FastByteBuffer buf = new FastByteBuffer();
+        assertEquals(FastByteBuffer.DEFAULT_MAX_CAPACITY, buf.getMaxCapacity());
+        assertEquals(131072, buf.getMaxCapacity());
+    }
 }

lib3270j/src/test/java/haus/nightmare/lib3270j/ft/FTConfigTest.java

@@ -187,4 +187,33 @@ public class FTConfigTest {
         assertEquals(FTConfig.AllocationUnit.TRACKS, config.getUnits());
         assertTrue(config.buildCommand().contains("SPACE(12,4,8) TRACKS"));
     }
+
+    @Test
+    public void testSetOverwriteDoesNotEmitReplaceOnSend() {
+        FTConfig config = new FTConfig();
+        config.setHostType(FTConfig.HostType.CMS);
+        config.setDirection(FTConfig.Direction.SEND);
+        config.setHostFilename("TEST FILE A");
+        config.setTransferMode(FTConfig.TransferMode.ASCII);
+        config.setCrAction(FTConfig.CrAction.REMOVE);
+        config.setOverwrite(true);
+
+        assertEquals("IND$FILE PUT TEST FILE A (ASCII CRLF", config.buildCommand());
+    }
+
+    @Test
+    public void testCmsSendIgnoresBlksizeAndReplace() {
+        FTConfig config = new FTConfig();
+        config.setHostType(FTConfig.HostType.CMS);
+        config.setDirection(FTConfig.Direction.SEND);
+        config.setHostFilename("TEST FILE A");
+        config.setTransferMode(FTConfig.TransferMode.ASCII);
+        config.setCrAction(FTConfig.CrAction.REMOVE);
+        config.setRecfm("F");
+        config.setLrecl("80");
+        config.setBlksize("800");
+        config.setExistAction(FTConfig.ExistAction.REPLACE);
+
+        assertEquals("IND$FILE PUT TEST FILE A (ASCII CRLF RECFM F LRECL 80", config.buildCommand());
+    }
 }

lib3270j/src/test/java/haus/nightmare/lib3270j/ft/FTDftTest.java

@@ -576,4 +576,96 @@ public class FTDftTest {
         assertTrue(ftDft.resendInboundDataBufferToHost());
         assertEquals(2, inputProcessor.sentStructuredFields.size());
     }
+
+    @Test
+    public void testZosUploadRecfmVAndFNormalizesAllNewlineVariants() {
+        FTConfig config = new FTConfig();
+        config.setDirection(FTConfig.Direction.SEND);
+        config.setHostType(FTConfig.HostType.TSO);
+        config.setHostFilename("'USER.TEST.DATA'");
+        config.setTransferMode(FTConfig.TransferMode.ASCII);
+        config.setCrAction(FTConfig.CrAction.REMOVE);
+        config.setRemapFlag(true);
+        config.setRecfm("V");
+        config.setLrecl("255");
+        listener.config = config;
+
+        // Mix \n, \r\n, \n\r (\c\r), bare \r, and \r\r\n
+        String originalText = "LINE1\nLINE2\r\nLINE3\n\rLINE4\rLINE5\r\r\n";
+        ByteArrayInputStream in = new ByteArrayInputStream(originalText.getBytes(StandardCharsets.ISO_8859_1));
+        ftDft.initTransfer(in, null);
+
+        byte[] getReq = new byte[] {
+            (byte) 0x00, (byte) 0x05, (byte) SF_TRANSFER_DATA,
+            (byte) (TR_GET_REQ >> 8), (byte) (TR_GET_REQ & 0xFF)
+        };
+        ftDft.processStructuredField(getReq, 0, getReq.length);
+
+        assertEquals(1, inputProcessor.sentStructuredFields.size());
+        byte[] payload = extractDataFromGetReply(inputProcessor.sentStructuredFields.get(0));
+
+        StringBuilder sb = new StringBuilder();
+        for (byte b : payload) {
+            int ub = b & 0xFF;
+            if (ub == 0x0D) {
+                sb.append("\r");
+            } else if (ub == 0x0A) {
+                sb.append("\n");
+            } else {
+                int ebc = ASC2FT[ub];
+                sb.append(translator.ebcdicToUnicode(ebc));
+            }
+        }
+
+        assertEquals("LINE1\r\nLINE2\r\nLINE3\r\nLINE4\r\nLINE5\r\n", sb.toString());
+    }
+
+    @Test
+    public void testZvmUploadOpenWithSizeAndCloseLifecycle() {
+        FTConfig config = new FTConfig();
+        config.setDirection(FTConfig.Direction.SEND);
+        config.setHostType(FTConfig.HostType.CMS);
+        config.setHostFilename("TEST EXEC A");
+        config.setTransferMode(FTConfig.TransferMode.ASCII);
+        config.setCrAction(FTConfig.CrAction.REMOVE);
+        config.setRemapFlag(true);
+        listener.config = config;
+
+        String originalText = "/* REXX */\nSAY 'HELLO FROM Z/VM'\nEXIT 0\n";
+        ByteArrayInputStream in = new ByteArrayInputStream(originalText.getBytes(StandardCharsets.UTF_8));
+        ftDft.initTransfer(in, null);
+
+        // Simulate z/VM 41-byte (0x0029) OpenForUploadWithSize with recsz = 16 (0x0010) at offset 30..31
+        byte[] openWithSize = new byte[41];
+        openWithSize[0] = 0x00;
+        openWithSize[1] = 0x29;
+        openWithSize[2] = (byte) SF_TRANSFER_DATA;
+        openWithSize[3] = (byte) (TR_OPEN_REQ >> 8);
+        openWithSize[4] = (byte) (TR_OPEN_REQ & 0xFF);
+        openWithSize[30] = 0x00;
+        openWithSize[31] = 0x10; // recsz = 16
+        byte[] ftDataName = "FT:DATA".getBytes(StandardCharsets.US_ASCII);
+        System.arraycopy(ftDataName, 0, openWithSize, 34, ftDataName.length);
+
+        ftDft.processStructuredField(openWithSize, 0, openWithSize.length);
+        assertTrue(listener.dftRunningCalled);
+        assertEquals(16, ftDft.getHostLrecl());
+
+        // Request 1st chunk — must be capped at recsz = 16 bytes
+        byte[] getReq = new byte[] {
+            0x00, 0x05, (byte) SF_TRANSFER_DATA,
+            (byte) (TR_GET_REQ >> 8), (byte) (TR_GET_REQ & 0xFF)
+        };
+        ftDft.processStructuredField(getReq, 0, getReq.length);
+        byte[] chunk1 = extractDataFromGetReply(inputProcessor.sentStructuredFields.get(1));
+        assertEquals(16, chunk1.length);
+
+        // Close FT:DATA stream — should NOT mark transfer complete before FT:MSG
+        byte[] closeReq = new byte[] {
+            0x00, 0x05, (byte) SF_TRANSFER_DATA,
+            (byte) (TR_CLOSE_REQ >> 8), (byte) (TR_CLOSE_REQ & 0xFF)
+        };
+        ftDft.processStructuredField(closeReq, 0, closeReq.length);
+        assertFalse(listener.completeCalled, "Closing FT:DATA should wait for FT:MSG before completing");
+    }
 }

lib3270j/src/test/java/haus/nightmare/lib3270j/ft/FTPhase3Test.java

@@ -88,10 +88,17 @@ public class FTPhase3Test {
         config.setLrecl(80);
 
         String cmd = config.buildCommand();
-        assertTrue(cmd.contains("REPLACE"));
-        assertTrue(cmd.contains("BLOCK 4096"));
+        assertFalse(cmd.contains("REPLACE"));
+        assertFalse(cmd.contains("BLOCK 4096"));
         assertTrue(cmd.contains("RECFM F"));
         assertTrue(cmd.contains("LRECL 80"));
+
+        config.setHostType(FTConfig.HostType.TSO);
+        config.setHostFilename("'USER.TEST.DATA'");
+        String tsoCmd = config.buildCommand();
+        assertTrue(tsoCmd.contains("BLKSIZE(4096)"));
+        assertTrue(tsoCmd.contains("RECFM(F)"));
+        assertTrue(tsoCmd.contains("LRECL(80)"));
     }
 
     @Test

lib3270j/src/test/java/haus/nightmare/lib3270j/ft/FTProtocolHardeningPhase16Test.java

@@ -293,12 +293,14 @@ public class FTProtocolHardeningPhase16Test {
         FTConfig config = new FTConfig();
         config.setDirection(FTConfig.Direction.SEND);
         config.setTransferMode(FTConfig.TransferMode.ASCII);
+        config.setCrFlag(true);
+        config.setRemapFlag(false);
         config.setRecfm(FTConfig.RecordFormat.FIXED);
         config.setLrecl("10");
         listener.config = config;
 
-        // Local content has two lines: "SHORT" (5 chars) and "LONGER LINE THAN TEN" (20 chars)
-        String localContent = "SHORT\nLONGER LINE THAN TEN\n";
+        // Local content has mixed newline styles (\n, \r\n, \n\r)
+        String localContent = "SHORT\nLONGER LINE\r\nTHIRD\n\r";
         ByteArrayInputStream in = new ByteArrayInputStream(localContent.getBytes(StandardCharsets.UTF_8));
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         ftDft.initTransfer(in, out);
@@ -311,16 +313,9 @@ public class FTProtocolHardeningPhase16Test {
         byte[] reply = input.sentStructuredFields.get(0);
         int headerLen = 17;
         int dataLen = reply.length - headerLen;
-        assertTrue(dataLen >= 30, "Should have packed at least 3 fixed records of 10 bytes each");
 
-        String rec1 = new String(reply, headerLen, 10, StandardCharsets.UTF_8);
-        assertEquals("SHORT     ", rec1);
-
-        String rec2 = new String(reply, headerLen + 10, 10, StandardCharsets.UTF_8);
-        assertEquals("LONGER LIN", rec2);
-
-        String rec3 = new String(reply, headerLen + 20, 10, StandardCharsets.UTF_8);
-        assertEquals("E THAN TEN", rec3);
+        String payload = new String(reply, headerLen, dataLen, StandardCharsets.UTF_8);
+        assertEquals("SHORT\r\nLONGER LINE\r\nTHIRD\r\n", payload);
     }
 
     @Test
@@ -328,6 +323,8 @@ public class FTProtocolHardeningPhase16Test {
         FTConfig config = new FTConfig();
         config.setDirection(FTConfig.Direction.RECEIVE);
         config.setTransferMode(FTConfig.TransferMode.ASCII);
+        config.setCrFlag(true);
+        config.setRemapFlag(false);
         config.setRecfm(FTConfig.RecordFormat.FIXED);
         config.setLrecl("10");
         listener.config = config;
@@ -336,8 +333,8 @@ public class FTProtocolHardeningPhase16Test {
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         ftDft.initTransfer(in, out);
 
-        // Host sends 10-byte fixed record "HELLO     "
-        byte[] hostRecord = "HELLO     ".getBytes(StandardCharsets.UTF_8);
+        // Host sends CRLF-terminated record "HELLO\r\n" + EOF (0x1A)
+        byte[] hostRecord = "HELLO\r\n\u001a".getBytes(StandardCharsets.UTF_8);
         ByteArrayOutputStream sf = new ByteArrayOutputStream();
         sf.write(0x00); sf.write(hostRecord.length + 8);
         sf.write(SF_TRANSFER_DATA);
@@ -353,17 +350,19 @@ public class FTProtocolHardeningPhase16Test {
 
         ftDft.processStructuredField(pkt, 0, pkt.length);
 
-        // Verify output has "HELLO" stripped of trailing spaces plus local line separator
+        // Verify output has CR and ^Z stripped
         String result = new String(out.toByteArray(), StandardCharsets.UTF_8);
-        assertEquals("HELLO" + System.lineSeparator(), result);
+        assertEquals("HELLO\n", result);
     }
 
     @Test
     public void testRecfmVRdwUploadAndDownload() throws Exception {
-        // 1. Upload RECFM V
+        // 1. Upload RECFM V (stream CRLF-normalized, no binary RDW injection in ASCII mode)
         FTConfig sendConfig = new FTConfig();
         sendConfig.setDirection(FTConfig.Direction.SEND);
         sendConfig.setTransferMode(FTConfig.TransferMode.ASCII);
+        sendConfig.setCrFlag(true);
+        sendConfig.setRemapFlag(false);
         sendConfig.setRecfm(FTConfig.RecordFormat.VARIABLE);
         listener.config = sendConfig;
 
@@ -378,37 +377,29 @@ public class FTProtocolHardeningPhase16Test {
         assertEquals(1, input.sentStructuredFields.size());
         byte[] reply = input.sentStructuredFields.get(0);
         int headerLen = 17;
-
-        // Verify 4-byte RDW header: length should be testLine.length() + 4
-        int rdwLen = ((reply[headerLen] & 0xFF) << 8) | (reply[headerLen + 1] & 0xFF);
-        assertEquals(testLine.length() + 4, rdwLen);
-        assertEquals(0, reply[headerLen + 2]);
-        assertEquals(0, reply[headerLen + 3]);
-        String payload = new String(reply, headerLen + 4, testLine.length(), StandardCharsets.UTF_8);
-        assertEquals(testLine, payload);
+        String payload = new String(reply, headerLen, reply.length - headerLen, StandardCharsets.UTF_8);
+        assertEquals(testLine + "\r\n", payload);
 
         // 2. Download RECFM V
         FTConfig recvConfig = new FTConfig();
         recvConfig.setDirection(FTConfig.Direction.RECEIVE);
         recvConfig.setTransferMode(FTConfig.TransferMode.ASCII);
+        recvConfig.setCrFlag(true);
+        recvConfig.setRemapFlag(false);
         recvConfig.setRecfm(FTConfig.RecordFormat.VARIABLE);
         listener.config = recvConfig;
 
         ByteArrayOutputStream downOut = new ByteArrayOutputStream();
         ftDft.initTransfer(new ByteArrayInputStream(new byte[0]), downOut);
 
-        // Host sends RDW header + "TEST V DATA"
-        byte[] vData = "TEST V DATA".getBytes(StandardCharsets.UTF_8);
-        int vRdwLen = vData.length + 4;
+        byte[] vData = "TEST V DATA\r\n".getBytes(StandardCharsets.UTF_8);
         ByteArrayOutputStream sfDown = new ByteArrayOutputStream();
         sfDown.write(0x00); sfDown.write(0x00);
         sfDown.write(SF_TRANSFER_DATA);
         sfDown.write(0x47); sfDown.write(0x04);
         sfDown.write(TR_BEGIN_DATA);
-        int fLen = vRdwLen + 5;
+        int fLen = vData.length + 5;
         sfDown.write((fLen >> 8) & 0xFF); sfDown.write(fLen & 0xFF);
-        sfDown.write((vRdwLen >> 8) & 0xFF); sfDown.write(vRdwLen & 0xFF);
-        sfDown.write(0x00); sfDown.write(0x00);
         sfDown.write(vData);
 
         byte[] downPkt = sfDown.toByteArray();
@@ -418,7 +409,7 @@ public class FTProtocolHardeningPhase16Test {
         ftDft.processStructuredField(downPkt, 0, downPkt.length);
 
         String downResult = new String(downOut.toByteArray(), StandardCharsets.UTF_8);
-        assertEquals("TEST V DATA" + System.lineSeparator(), downResult);
+        assertEquals("TEST V DATA\n", downResult);
     }
 
     @Test

lib3270j/src/test/java/haus/nightmare/lib3270j/telnet/FramingBufferBoundedCapTest.java

@@ -0,0 +1,234 @@
+package haus.nightmare.lib3270j.telnet;
+
+import haus.nightmare.lib3270j.ConnectionConfig;
+import haus.nightmare.lib3270j.ConnectionState;
+import haus.nightmare.lib3270j.TerminalModel;
+import haus.nightmare.lib3270j.charset.EbcdicTranslator;
+import haus.nightmare.lib3270j.datastream.DataStreamProcessor;
+import haus.nightmare.lib3270j.nvt.NvtProcessor;
+import haus.nightmare.lib3270j.printer.PrinterConfig;
+import haus.nightmare.lib3270j.printer.Telnet3270EP;
+import haus.nightmare.lib3270j.protocol.TelnetConstants;
+import haus.nightmare.lib3270j.screen.ScreenBuffer;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import static haus.nightmare.lib3270j.protocol.TelnetConstants.*;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class FramingBufferBoundedCapTest {
+
+    private ConnectionConfig config;
+    private ScreenBuffer screenBuffer;
+    private DataStreamProcessor dsProcessor;
+    private TelnetFSM fsm;
+    private MockConnection connection;
+
+    private static class MockConnection extends TelnetConnection {
+        final List<byte[]> sentData = new ArrayList<>();
+
+        MockConnection(ConnectionConfig config, TelnetFSM fsm) {
+            super(config, fsm);
+        }
+
+        @Override
+        public synchronized void sendRaw(byte[] data) {
+            sentData.add(data.clone());
+        }
+
+        @Override
+        public synchronized void sendRaw(byte[] data, int offset, int length) {
+            byte[] b = new byte[length];
+            System.arraycopy(data, offset, b, 0, length);
+            sentData.add(b);
+        }
+    }
+
+    @BeforeEach
+    public void setup() {
+        config = new ConnectionConfig("localhost", 23, TerminalModel.IBM_3279_4);
+        screenBuffer = new ScreenBuffer(TerminalModel.IBM_3279_4, new EbcdicTranslator());
+        dsProcessor = new DataStreamProcessor(screenBuffer, new EbcdicTranslator());
+        fsm = new TelnetFSM(config, screenBuffer, dsProcessor);
+        haus.nightmare.lib3270j.input.InputProcessor inputProcessor =
+                new haus.nightmare.lib3270j.input.InputProcessor(screenBuffer, new EbcdicTranslator(), fsm);
+        dsProcessor.setInputProcessor(inputProcessor);
+        connection = new MockConnection(config, fsm);
+        fsm.setConnection(connection);
+    }
+
+    private void feedBytes(int... bytes) {
+        byte[] b = new byte[bytes.length];
+        for (int i = 0; i < bytes.length; i++) {
+            b[i] = (byte) bytes[i];
+        }
+        fsm.feedBytes(b, 0, b.length);
+    }
+
+    @Test
+    @DisplayName("Framing buffer caps at 128KB and enters discard mode if stream lacks IAC EOR")
+    public void testFramingBufferOverflowDiscardsUntilEor() {
+        fsm.onConnected();
+
+        // Negotiate BINARY and EOR to establish standard 3270 streaming regime
+        feedBytes(IAC, DO, TELOPT_EOR);
+        feedBytes(IAC, WILL, TELOPT_EOR);
+        feedBytes(IAC, DO, TELOPT_BINARY);
+        feedBytes(IAC, WILL, TELOPT_BINARY);
+
+        assertEquals(131072, fsm.getMaxFramingBufferSize(), "Default framing buffer cap should be 128KB (131072 bytes)");
+        assertFalse(fsm.isRecordDiscardMode());
+
+        // Feed chunks totaling over 128KB without any IAC EOR delimiter
+        byte[] chunk = new byte[8192];
+        Arrays.fill(chunk, (byte) 0xC1); // EBCDIC 'A'
+
+        for (int i = 0; i < 16; i++) {
+            fsm.feedBytes(chunk, 0, chunk.length); // 16 * 8192 = 131,072 bytes
+        }
+        assertFalse(fsm.isRecordDiscardMode(), "Buffer should be at exact cap without overflowing yet");
+
+        // Now feed an additional chunk exceeding the 128KB cap without IAC EOR
+        fsm.feedBytes(chunk, 0, 100);
+
+        assertTrue(fsm.isRecordDiscardMode(), "FSM must enter recordDiscardMode when cap is exceeded without IAC EOR");
+        assertEquals(0, fsm.getCurrentFramingBufferSize(), "Buffer must be reset to free memory upon overflow");
+
+        // Further incoming data without IAC EOR must be discarded without growing the buffer
+        fsm.feedBytes(chunk, 0, chunk.length);
+        assertEquals(0, fsm.getCurrentFramingBufferSize(), "Discard mode must drop subsequent data without accumulating memory");
+        assertTrue(fsm.isRecordDiscardMode());
+
+        // Feeding IAC EOR must clear discard mode and reset buffer cleanly
+        feedBytes(IAC, EOR);
+        assertFalse(fsm.isRecordDiscardMode(), "IAC EOR must clear recordDiscardMode");
+        assertEquals(0, fsm.getCurrentFramingBufferSize());
+
+        // A subsequent valid record must be processed normally
+        // 0xF5 (Erase/Write), 0xC2 (WCC: unlock keyboard), 0x11 (SBA), 0x00, 0x00, 0xC1 ('A'), IAC, EOR
+        byte[] valid3270 = new byte[] { (byte) 0xF5, (byte) 0xC2, (byte) 0x11, 0x00, 0x00, (byte) 0xC1, (byte) IAC, (byte) EOR };
+        fsm.feedBytes(valid3270, 0, valid3270.length);
+
+        assertEquals('A', screenBuffer.getDisplayCell(0).ucs4);
+    }
+
+    @Test
+    @DisplayName("Custom maxFramingBufferSize on ConnectionConfig is respected by TelnetFSM")
+    public void testCustomMaxFramingBufferSize() {
+        ConnectionConfig customConfig = new ConnectionConfig("localhost", 23, TerminalModel.IBM_3279_4);
+        customConfig.setMaxFramingBufferSize(1024); // 1KB custom limit
+
+        TelnetFSM customFsm = new TelnetFSM(customConfig, screenBuffer, dsProcessor);
+        customFsm.setConnection(connection);
+        customFsm.onConnected();
+
+        assertEquals(1024, customFsm.getMaxFramingBufferSize());
+
+        // Negotiate BINARY and EOR
+        byte[] neg = new byte[] {
+            (byte) IAC, (byte) DO, (byte) TELOPT_EOR,
+            (byte) IAC, (byte) WILL, (byte) TELOPT_EOR,
+            (byte) IAC, (byte) DO, (byte) TELOPT_BINARY,
+            (byte) IAC, (byte) WILL, (byte) TELOPT_BINARY
+        };
+        customFsm.feedBytes(neg, 0, neg.length);
+
+        byte[] payload500 = new byte[500];
+        Arrays.fill(payload500, (byte) 0xC1);
+        customFsm.feedBytes(payload500, 0, 500);
+        assertEquals(500, customFsm.getCurrentFramingBufferSize());
+        assertFalse(customFsm.isRecordDiscardMode());
+
+        customFsm.feedBytes(payload500, 0, 500);
+        assertEquals(1000, customFsm.getCurrentFramingBufferSize());
+        assertFalse(customFsm.isRecordDiscardMode());
+
+        // Overflow over 1024 limit
+        customFsm.feedBytes(payload500, 0, 100);
+        assertTrue(customFsm.isRecordDiscardMode());
+        assertEquals(0, customFsm.getCurrentFramingBufferSize());
+    }
+
+    @Test
+    @DisplayName("Telnet subnegotiation buffer caps at 8KB if stream lacks IAC SE without leaking into data buffer")
+    public void testSubnegotiationBufferCap() {
+        fsm.onConnected();
+        feedBytes(IAC, DO, TELOPT_EOR);
+        feedBytes(IAC, WILL, TELOPT_EOR);
+        feedBytes(IAC, DO, TELOPT_BINARY);
+        feedBytes(IAC, WILL, TELOPT_BINARY);
+
+        // Begin subnegotiation: IAC SB TELOPT_TTYPE
+        feedBytes(IAC, SB, TELOPT_TTYPE);
+
+        // Feed > 8192 bytes without IAC SE
+        byte[] largeSb = new byte[9000];
+        Arrays.fill(largeSb, (byte) 'X');
+        fsm.feedBytes(largeSb, 0, largeSb.length);
+
+        // Overflowing SB bytes must NOT leak into the 3270 framing buffer while waiting for IAC SE
+        assertEquals(0, fsm.getCurrentFramingBufferSize(), "Overflowing SB bytes must not leak into ibuf");
+
+        // Terminate the subnegotiation with IAC SE
+        feedBytes(IAC, SE);
+        assertEquals(0, fsm.getCurrentFramingBufferSize());
+
+        // Subsequent 3270 data record should be processed cleanly
+        byte[] valid3270 = new byte[] { (byte) 0xF5, (byte) 0xC2, (byte) 0x11, 0x00, 0x00, (byte) 0xC1, (byte) IAC, (byte) EOR };
+        fsm.feedBytes(valid3270, 0, valid3270.length);
+        assertEquals('A', screenBuffer.getDisplayCell(0).ucs4);
+    }
+
+    @Test
+    @DisplayName("Printer framing buffer caps at 128KB and enters discard mode without IAC EOR")
+    public void testPrinterFramingBufferCap() throws Exception {
+        PrinterConfig pcfg = new PrinterConfig("localhost", 23);
+        assertEquals(131072, pcfg.getMaxFramingBufferSize());
+
+        Telnet3270EP printer = new Telnet3270EP(pcfg);
+        assertEquals(131072, printer.getMaxFramingBufferSize());
+        assertFalse(printer.isRecordDiscardMode());
+
+        Method processIncoming = Telnet3270EP.class.getDeclaredMethod("processIncomingBytes", byte[].class, int.class, int.class);
+        processIncoming.setAccessible(true);
+
+        byte[] chunk = new byte[8192];
+        Arrays.fill(chunk, (byte) 0x40);
+
+        for (int i = 0; i < 17; i++) {
+            processIncoming.invoke(printer, chunk, 0, chunk.length); // 17 * 8192 = 139,264 bytes > 131,072
+        }
+
+        assertTrue(printer.isRecordDiscardMode(), "Printer must enter discard mode when record exceeds 128KB");
+
+        // Send IAC EOR
+        byte[] eor = new byte[] { (byte) IAC, (byte) EOR };
+        processIncoming.invoke(printer, eor, 0, eor.length);
+
+        assertFalse(printer.isRecordDiscardMode(), "Printer must clear discard mode on IAC EOR");
+    }
+
+    @Test
+    @DisplayName("NvtProcessor caps escape sequence buffer at 4KB if terminator is missing")
+    public void testNvtProcessorEscapeBufferCap() {
+        NvtProcessor nvt = fsm.getNvtProcessor();
+
+        // Stream ESC [ followed by 5000 digits without terminating byte (0x40..0x7E)
+        byte[] escStart = new byte[] { 0x1B, '[' };
+        nvt.processNVTData(escStart, 0, escStart.length);
+
+        byte[] digits = new byte[5000];
+        Arrays.fill(digits, (byte) '1');
+        nvt.processNVTData(digits, 0, digits.length);
+
+        // After escBuffer reaches 4096 bytes, it aborts escape parsing and returns to STATE_NORMAL.
+        // Subsequent digits are rendered as plain text in the screen buffer starting at cell 0.
+        assertEquals('1', screenBuffer.getCell(0).ucs4);
+    }
+}

setup.ps1

@@ -417,7 +417,7 @@ if (Test-Path $libResDir) {
 # ------------------------------------------------------------------------------
 Write-LogInfo "Packaging standalone lib3270j library JAR..."
 $libManifestFile = Join-Path $BuildDir "LIB_MANIFEST.MF"
-$libManifestText = "Manifest-Version: 1.0`r`nImplementation-Title: lib3270j`r`nImplementation-Version: 1.2.4`r`nCreated-By: j3270 setup.ps1`r`n`r`n"
+$libManifestText = "Manifest-Version: 1.0`r`nImplementation-Title: lib3270j`r`nImplementation-Version: 1.2.5`r`nCreated-By: j3270 setup.ps1`r`n`r`n"
 [System.IO.File]::WriteAllText($libManifestFile, $libManifestText)
 
 $libJarFile = Join-Path $BuildDir "lib3270j.jar"
@@ -425,7 +425,7 @@ $libJarFile = Join-Path $BuildDir "lib3270j.jar"
 
 Write-LogInfo "Packaging standalone executable JAR..."
 $manifestFile = Join-Path $BuildDir "MANIFEST.MF"
-$manifestText = "Manifest-Version: 1.0`r`nMain-Class: haus.nightmare.j3270.J3270App`r`nImplementation-Title: j3270`r`nImplementation-Version: 1.2.4`r`nCreated-By: j3270 setup.ps1`r`n`r`n"
+$manifestText = "Manifest-Version: 1.0`r`nMain-Class: haus.nightmare.j3270.J3270App`r`nImplementation-Title: j3270`r`nImplementation-Version: 1.2.5`r`nCreated-By: j3270 setup.ps1`r`n`r`n"
 [System.IO.File]::WriteAllText($manifestFile, $manifestText)
 
 $jarFile = Join-Path $BuildDir "j3270.jar"

setup.sh

@@ -376,7 +376,7 @@ log_info "Packaging standalone lib3270j library JAR..."
 cat << 'EOF' > "$BUILD_DIR/LIB_MANIFEST.MF"
 Manifest-Version: 1.0
 Implementation-Title: lib3270j
-Implementation-Version: 1.2.4
+Implementation-Version: 1.2.5
 Created-By: j3270 setup.sh
 
 EOF
@@ -390,7 +390,7 @@ cat << 'EOF' > "$BUILD_DIR/MANIFEST.MF"
 Manifest-Version: 1.0
 Main-Class: haus.nightmare.j3270.J3270App
 Implementation-Title: j3270
-Implementation-Version: 1.2.4
+Implementation-Version: 1.2.5
 Created-By: j3270 setup.sh
 
 EOF