OA45064: ABEND0A9 7075 ISTORCDF+X'39C' DOUBLE FREEBLK WHILE RUNNING TN3270

Obtain the fix for this APAR.

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:                                              *
  * Apply PTF.                                                   *
  ****************************************************************
  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 is sysrouted FROM one or more of the following:

  OA44909

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

  UA73351

Modules/Macros

• ISTTSCDU
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R210 PSY UA73351

     UP14/06/14 P F406

Fix is available

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