A fix is available
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 number
PH11462
Reported component name
IBM MQ Z/OS V9
Reported component ID
5655MQ900
Reported release
000
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-04-26
Closed date
2019-11-26
Last modified date
2020-02-04
APAR is sysrouted FROM one or more of the following:
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
Fix is available
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Document Information
Modified date:
04 February 2020