A fix is available
APAR status
Closed as program error.
Error description
A WebSphere Application Server (WAS) log contains error: JMSCMQ0001: WEBSPHERE MQ CALL FAILED WITH REASON '2352' ('MQRC_LOCAL_UOW_CONFLICT') A timing window is exposed by tasks that are attempting to switch to an incorrect context and failing with MQRC_LOCAL_UOW_CONFLICT reason 2352. CSQMCPRH expresses interest in the provided context and determines that the context is already associated with another task - this is unexpected and correctly results in the MQRC_LOCAL_UOW_CONFLICT error being returned. However if that specific context is being committed at the same time, an error in serialization of the context ACE between CSQMCPRH and CSQ3RRSM (the RRS exit performing the commit) can lead to the 0C4 in CSQ3RRSM seen in the initial dump. The dump title says M=CSQ3RRSF, but the PSW is in CSECT CSQ3RRSM. If CSQ3RRSM is driven from a different home address space than CSQMCPRH is running under (in the dump, CSQ3RRSM had been invoked from a TCB in the RRS address space rather than one in the Servant region address space), the context ACE can be left on the VLCAAACE chain for the servant region following recovery for the 0C4, resulting in other potential errors, including a loop in the chain such as the one that was preventing the servant region shutting down. The stack associated with the ABEND0C4: Native traceback: __zerro +0000120C __zerros +00000306 CEEHDSP +000044AE CEEOSIGJ +00000962 CELQHROD +00000266 CEEOSIGG +00000000 CELQHROD +00000266 CSQBDspiOPEN+00000834 CSQBLB56 ***Exception Java_com_ibm_mq_jmqi_local_internal_base_Native_spiOpen RUNJAVATHREAD ... Java stack: at com/ibm/mq/jmqi/local/internal/base/Native.spiOpen(Native Method) at com/ibm/mq/jmqi/local/LocalMQ.spiOpen(Bytecode PC:762(Compiled Code)) at com/ibm/msg/client/wmq/internal/WMQConsumerShadow.initialize(Byt ecode PC:1732(Compiled Code)) at com/ibm/msg/client/wmq/internal/WMQSyncConsumerShadow.initialize (Bytecode PC:15(Compiled Code)) * Additional keywords: ACECHNA loop
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM MQ for z/OS Version 9 * * Release 1 Modification 0 and Release 2 * * Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: Inadequate serialisation between RRS * * tasks can result in an ABEND0C4 in * * CSQ3RRSM. The timing window which * * results in this problem may be * * accompanied by applications receiving * * MQRC_LOCAL_UOW_CONFLICT and * * MQRC_GLOBAL_UOW_CONFLICT. * **************************************************************** CSQ3RRSM is invoked as part of RRS exit processing, and a timing window exists whereby the ACEATEB field is cleared while the ACE is still in-use. Consequently, attempts to set fields chained from it will cause an S0C4 abend.
Problem conclusion
The serialisation of RRS exit processing has been improved to prevent ACEAETB being cleared while the ACE is still in use.
Temporary fix
Comments
APAR Information
APAR number
PH26279
Reported component name
IBM MQ Z/OS V9
Reported component ID
5655MQ900
Reported release
100
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2020-06-09
Closed date
2020-11-09
Last modified date
2021-01-04
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI72460 UI72461
Modules/Macros
CSQ3RRSM CSQMCPRH
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:
05 January 2021