PH11867: CICS TRANSACTION CRST LOOPS AND ABENDS AKEC AS A RUNAWAY TASK. DFHRS0007E MAY ALSO APPEAR.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Your CICS region experiences an AKEC abend in tran CRST for
  exceeding the ICVR value. You may also (but no necessarily) see
  DFHRS0007E.
  .
  .
  Additional Symptom(s) Search Keyword(s): KIXREVxxx
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: CICSPlex SM users using sysplex optimised    *
  *                 workload management.                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: The CICS RS domain long running task    *
  *                      CRST gets caught running a tight loop   *
  *                      and is abended by CICS runaway.         *
  *                      CICS issues msgDFHRS0004                *
  *                      +DFHRS0004 applid A possible loop has   *
  *                         been detected at offset X'FFFF'      *
  *                         in module DFHRSTP.                   *
  ****************************************************************
  When a user task executing in CICS issues a transaction dump,
  CICS RS domain (DFHRSDU) is notified (RSDU START_TDUMP). This
  updates the region status record in the DFHRSTAT coupling
  facility data table, to show that a dump is in progress. When
  the transaction dump completes RS domain will be notified again
  (RSDU STOP_TDUMP). DFHRSTAT is not updated again immediately.
  Instead the RS domain long running task CRST is notified. The
  CRST task will process this notification after a short delay,
  and will sleep until then.
  .
  After one second has passed, the CRST task will wake up and be
  redispatched on the QR TCB. At this time it will attempt to
  update DFHRSTAT (dump no longer in progress). In the reported
  problem, another task in the system happened to be in
  termination. That task ending causes the task load in the region
  to drop down one tier boundary (see UPDATERS), which causes the
  task to update DFHRSTAT. This task happened to be executing
  under an open TCB, and so attempted to switch to the QR TCB to
  complete the CFDT request.
  .
  This created a deadlock between the two tasks. The user task
  could not get dispatched under QR to complete the CFDT request
  because CRST was executing on the QR TCB. A logic error in
  program DFHRSTP meant that it entered a loop which it then could
  not exit until the currently in flight CFDT update had
  completed. The deadlock condition is eventually terminated when
  the CICS Runaway interval (as controlled by the ICVR system
  initialization parameter) expires. At that time the CRST task
  is purged. CICS will issue message DFHRS0004 and then
  automatically restart the CRST task.
  .
  +DFHRS0004 applid A possible loop has been detected at offset
  X'FFFF' in module DFHRSTP.
  .
  Additional Keywords: RS0004 rstp_proc_loop CF_update_in_progress
  AKEC abendAKEC
  

Problem conclusion

• DFHRSTP has been updated to avoid the loop condition when
  another task is currently updating the CFDT.
  

Temporary fix

Comments

APAR Information

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

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

  UI65147 UI65148

Modules/Macros

• DFHRSTP
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R100 PSY UI65147

     UP19/09/07 P F909

• R200 PSY UI65148

     UP19/09/07 P F909

Fix is available

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