PH11462: PROVIDE AN ALTERNATIVE METHOD FOR THE IMS ADAPTER TO DETECT THE QUEUE MANAGER QUIESCING.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• For some IMS transactions, the cost of attaching/detaching
  the CSQQWAIT TCB can be significant.
  For other IMS transactions, the environment when CSQQTTHD runs
  does not allow the TCB to be posted and detached, leading to 0F8
  abends.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 0 Modification 0 and Release 1       *
  *                 Modification 0                               *
  ****************************************************************
  * PROBLEM DESCRIPTION: High CPU cost in IMS dependent regions  *
  *                      due to attach/detach processing for     *
  *                      CSQQWAIT in some environments.          *
  *                                                              *
  *                      In other environments, abend 0F8 can    *
  *                      occur when posting CSQQWAIT due to SVC  *
  *                      calls being disallowed.                 *
  ****************************************************************
  During ESAF signon exit processing, a TCB is attached to run
  CSQQWAIT, which monitors the queue manager for termination and
  posts any waiting getters in the IMS dependent region.
  The TCB is detached when the ESAF terminate thread or terminate
  identify exit runs.
  
  For some application designs, this can lead to attach/detach
  processing occurring very frequently, leading to unexpectedly
  high CPU cost.
  

Problem conclusion

• An alternative mode for CSQQWAIT is added, causing it to run as
  a STIMER exit, giving a potential reduction in the CPU cost for
  affected applications, and removing the need to issue the POST
  SVC call.
  The new mode is enabled using a queue manager tuning parameter.
  
  For applications where the existing mode does not lead to
  frequent attach/detach processing, there is a potential increase
  in CPU cost when using the alternative mode.
  
  For more information on enabling the alternative mode please
  contact IBM support.
  

Temporary fix

Comments

APAR Information

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

  PH10277

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

  UI66639 UI66640

Modules/Macros

• CSQ3ID30 CSQIRECP CSQQIDEN CSQQNORM CSQQSSON CSQQTTHD CSQQWAIT
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R000 PSY UI66639

     UP20/01/25 P F001

• R100 PSY UI66640

     UP20/01/27 P F001

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.