PM83790: CEX2 TRANSACTION LOOPING, TAKING 100% CPU AFTER MIDNIGHT WHEN THE MVS CLOCK HAS CHANGED

Rational Asset Manager Interim Fix 9 for 7.5.2
Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• You are running CICS Transaction Server 4.1 and
  notice the region is using 100% of the CPU.
  Transaction CEX2 was executing, over and over.
  We learned from the dump that the CICS clock was
  out of sync with the MVS clock. Looking at the
  message log we can see the MVS clock was set
  backwards by about 46 sesconds:
  .
  00.00.00---- THURSDAY,  14 FEB 2013 ----
  00.00.00 +DFHIC0801 APPLID CICS time altered from
            24.00.000 to 00.00.486 - date 14/02/13
  .
  Because of this time change, and CICS not being in
  sync with the system time, the CEX2 transaction, that
  should run every 30 seconds, was now getting kicked
  off immediately, taking up all the CPU.
  .
  They had AUTORESETTIME=NO. AUTORESETTIME=yes or issuing
  a CEMT PERFORM RESET would have corrected the
  situation. But there is an option
  AUTORESETTIME=IMMEDIATE, which is not full proof.
  It requires a new task to be kicked off, in order
  to take effect.  This APAR will address this odd
  case, where a new transaction does not get kicked
  off at midnight, when the immediate option is
  specified for AUTORESETTIME.
  .
  Additional Symptom(s) Search Keyword(s): KIXREVxxx
  

Local fix

• issue CEMT PERFORM RESET
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All.                                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: AUTORESETTIME=IMMEDIATE interpreted as  *
  *                      YES in specific circumstances.          *
  ****************************************************************
  * RECOMMENDATION:                                            . *
  ****************************************************************
  The AUTORESETTIME=IMMEDIATE parameter will synchronize the CICS
  internal clock with the MVS clock after the latter has been
  altered.  However, this only occurs if DFHAPIN is driven when a
  CICS user task is attached.
  It is quite usual to adjust the MVS clock backwards or
  forwards one hour consistent with daylight saving time but in
  the reported problem, the MVS clock was moved backwards circa
  50s at just before MVS midnight. Had a CICS user task been
  attached then a full resync would have occurred to sync the CICS
  clock with the MVS clock.
                                                                 .
  DFHAPTIM, the Interval Control Midnight Task program ran at
  CICS midnight but this is a system task that doesn't drive
  DFHAPIN.  DFHAPTIM contains code to sync the MVS and CICS
  clocks but a path exists where if it is driven within a 30
  minute window either side of MVS midnight then it will do a
  DFHIC reset as if AUTORESETTIME=YES was coded.  This will
  cause a DFHIC reset but the CICS internal clock is not synced
  with the MVS clock. This may have the unintended consequence
  for scheduled tasks whose Interval Control Elements ( ICE's )
  expire in ( say ) 30 seconds in that they start immediately.
  

Problem conclusion

• DFHAPTIM has been modified so that it will treat
  AUTORESETTIME=YES and AUTORESETTIME=IMMEDIATE as both requiring
  a full reset in this circumstance.
  

Temporary fix

• *********
              * HIPER *
              *********
  FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

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

  PM89639 UK95612 UK95613

Modules/Macros

• DFHAPTIM
  

Fix information

• Fixed component name

  CICS TS Z/OS V4

• Fixed component ID

  5655S9700

Applicable component levels

• R600 PSY UK95612

     UP13/07/13 P F307

• R700 PSY UK95613

     UP13/07/13 P F307

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.