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OA44909: ABEND0A9 7075 ISTORCDF+X'39C' DOUBLE FREEBLK WHILE RUNNING TN3270

A fix is available

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APAR status

  • Closed as program error.

Error description

  • While running TN3270, VTAM took a diagnostic abend0A9 when it
    attempted to free previously freed storage.  It set the return
    code of 7075 (FREEBLK issued for a previously freed storage
    area).  This was the result of two first-in-chain PIUs being
    received, which should have resulted in a TN3270 session failure
    with sense code 20020000 (chaining error), not an abend0a9.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of Telnet.                         *
    ****************************************************************
    * PROBLEM DESCRIPTION: ABEND0A9 in ISTORCDF in Telnet's        *
    *                      address space.                          *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The problem may be summarized as follows:
    1. A TN3270 connection comes up and a session is
       established.
    2. The PLU sends data (FIC) before the TN3270 server has
       put up a receive. The data is saved in the data space
       while waiting for the receive to be issued.
    3. The PLU sends more data and erroneously has FIC
       specified again.  The data is saved in the data space.
    4. The TN3270 server issues Receive and then ISTTSCDU
       starts processing the queued data.
    5. When ISTTSCDU encounters the second piece of data that
       indicated it was FIC, ISTTSCDU calls ISTTSCGR to reject
       this data with a sense of x'20020000'.  ISTTSCGR frees
       the storage and returns to ISTTSCDU.
    6. ISTTSCDU is called again with the same piece of storage
       because ISTTSCDU failed to remove it from the queue. This
       time, when ISTTSCGR tries to free the storage, ISTORCDF
       abends with ABEND0A9. There can be many ABEND0A9s in this
       case. (Another symptom may be ABEND0C4 in ISTTSCGR.)
    

Problem conclusion

  • ISTTSCDU is updated to gracefully handle the erroneous
    condition where a PLU sends two consecutive PIUs with FIC
    on in both of them.
    

Temporary fix

Comments

APAR Information

  • APAR number

    OA44909

  • Reported component name

    VTAM V4 MVS/ESA

  • Reported component ID

    569511701

  • Reported release

    1D0

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2014-03-31

  • Closed date

    2014-04-22

  • Last modified date

    2014-06-03

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

    UA73236 OA45064

Modules/Macros

  • ISTTSCDU
    

Fix information

  • Fixed component name

    VTAM V4 MVS/ESA

  • Fixed component ID

    569511701

Applicable component levels

  • R1D0 PSY UA73236

       UP14/05/22 P F405

Fix is available

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Document Information

Modified date:
03 June 2014