Tracing an IBM 3270 or 5250 Session

While troubleshooting a problem in an IBM 3270 or 5250 session, technical support may request that you obtain one or more traces. Three kinds of traces can be done: host-data, command, and HLLAPI.

Trace File Type


Host-data trace (*.hst)

Captures information passed between a terminal, or printer, session and the host. This type of trace is useful when a host connection is working, but the terminal or printer session does not behave as expected. Host traces are not useful when a connection to the host cannot be established.

Command trace (*.cmd)

Captures actions within InfoConnect. Each action, such as clicking a button or entering text, represents an individual command. Command traces are useful in determining if commands are correct in a script, macro, or program using OLE automation.

Command traces can also be used to determine which command to use when writing a script. Use a text editor to view the command trace and determine which commands are needed to accomplish the task.

HLLAPI trace

Enables you to see the HLLAPI calls the application is making, including return codes. (HLLAPI is an API specified by IBM for automating terminal tasks.)

To generate a host-data or command trace

  1. Open a session or create a new session.

  2. In the Start Trace dialog box, specify a name for the trace file. If you have spoken with a support technician, use your service request number as the name of your trace file.

    For this type of trace

    Use this extension

    Host data




  3. Click Save.

    "Tracing started..." displays in the InfoConnect status bar, indicating the trace is active.

  4. Perform the actions that reproduce the problem you want recorded in the trace.

To generate a HLLAPI trace

  1. Click the Windows Start button.

  2. In the Start Search box, type win.ini and press Enter to open your Win.ini file in Notepad.

  3. Add the following two lines to the end of the Win.ini file:

    [Reflection HLLAPI]
  4. In the InfoConnect Workspace, open a session or create a new session to connect to your IBM host.

  5. Start the HLLAPI application.

  6. Perform the actions that reproduce the problem you want recorded in the trace.

  7. Close the HLLAPI application.

    The trace file is automatically named HLL*.TMP, where * is a randomly generated hex number. The file is located in your system’s TEMP directory, if a TEMP directory has been defined in the System Environment settings. Otherwise, it is located in the root Windows directory.

  8. Re-open the Win.ini file, and change the ExtTraceOn setting to zero by changing the last line of the ini file: