A fix is available
APAR status
Closed as program error.
Error description
The customer was running WMQ V7.1 in a 3-way QSG with z/OS V2R1. While running some of their MQCICS workloads using shared queues they lost full connectivity to CF21 in which some simplex structures resided. They took a S0C4 dumps with one of the CICS regions. . IEA794I SVC DUMP HAS CAPTURED: DUMPID=025 REQUESTED BY JOB (IOSAS ) DUMP TITLE=COMPON=XES,COMPID=5752SCIXL,ISSUER=IXLM1REC, MODULE=IXLE1CRW,ABEND=S0026,REASON=07070001 . +DFHDU0201 CICS3A2A ABOUT TO TAKE SDUMP. DUMPCODE: MQ0480 , DUMPID: 1/0004 . IEA794I SVC DUMP HAS CAPTURED: DUMPID=026 REQUESTED BY JOB (CICS3A2A) DUMP TITLE=CSQ2,ABN=0C4-00000011,U=CICSTS ,C=R3600.710.CFM -CSQETHDP,M=CSQGFRCV,LOC=CSQELPLM.CSQETHDP . The change team reviewed the doc and the S026 abends appear to be linked to the 0C4 only in that they appear to relate to a loss of connection to the CF/structures, and the processing performed by MQ due to the connection loss led to the 0C4 occurring. The S026 abends do not appear to be related to MQ - VERBX MTRACE shows errors involving paths being stopped/restarted - if these were not expected these dumps would need to be looked at by XCF to determine the reason for the S026-07070001 abends. . They have now been able to identify the cause of the 0C4 in CSQETHDP, which occurs when a structure failure or loss of connectivity to a structure occurs while an MQPUT1 is in the process of putting to a shared queue on that structure. While handling the connection loss, MQ incorrectly frees control blocks relating to the queue that are still required by the MQPUT1 processing, leading to the abend 0C4 when they are next referenced.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 * * Release 1 Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: Abend 0C4 occurs in CSQETHDP or * * CSQMPOM if a structure fails or * * connection to a structure is lost while * * a message is being put to the queue by * * an MQPUT1 call or an internal put call. * * In some circumstances the abend is * * followed by abnormal queue manager * * termination S6C6 with REASON=00E50702 * **************************************************************** * RECOMMENDATION: * **************************************************************** During put processing for a shared queue, the queue manager detects that the structure containing the shared queue has failed, or lost connectivity to this queue manager. CSQISQC1 is called to decrement the uncommitted count for the queue and checks if the queue is currently in use. However in some cases, such as MQPUT1 calls or internal put calls, it can incorrectly determine that it is not in use. This causes the queue to be disconnected and the shared queue token to be freed. The abend occurs when put processing subsequently attempts to access the queue using the freed shared queue token.
Problem conclusion
Put processing is changed to correctly indicate that it is using a shared queue in the affected cases, preventing the queue being disconnected and the shared queue token being freed until after the put operation has finished using the queue. 100Y CSQESTFA CSQISQC1 CSQMCLSQ CSQMCSQ1 CSQMOSQ1
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
PI20312
Reported component name
WMQ Z/OS V7
Reported component ID
5655R3600
Reported release
100
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2014-06-18
Closed date
2014-07-31
Last modified date
2014-09-03
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI20126
Modules/Macros
CSQESTFA CSQISQC1 CSQMCLSQ CSQMCSQ1 CSQMOSQ1
Fix information
Fixed component name
WMQ Z/OS V7
Fixed component ID
5655R3600
Applicable component levels
R100 PSY UI20126
UP14/08/30 P F408 ¢
Fix is available
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Document Information
Modified date:
03 September 2014