A fix is available
APAR status
Closed as program error.
Error description
Level 3 sees that there is a window in which 64-bit storage contraction (as a result of the CSQY224E) can occur while a thread is in the process of obtaining a 64-bit quickcell element from the free-chain. The storage contraction (CSQSQC64) can then result in the freeing of the storage extent containing the allocated quickcell element, which results in the 0C4 seen here (this would occur if the storage contraction takes place after the CSQSGC64 macro has checked CSQS_QP64_UNIQ_RES1 but before the CSQSGC64 macro has set QCEL_64.csId. Additional Symptom(s) Search Keyword(s):
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 * * Release 1 Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: Erroneous free of 64bit quick cell pool * * storage when queue manager is * * undergoing cell pool contraction may * * result in S0C4 abends occurring. * **************************************************************** * RECOMMENDATION: * **************************************************************** When a queue manager is short on 64bit storage above the bar and issues message CSQY224I indicating that it is attempting to free all unused storage above the bar, it is possible that a timing condition occurs where a cell from a pool is allocated immediately before the pool contraction occurs, but it not marked as in use immediately. This in-use cell may be incorrectly classified as being free and the queue manager may subsequently free the extent even though there are elements in use. Once the storage has been freed, any procedure attempting to use the cell pool storage may abend with an S0C4.
Problem conclusion
Processing has been amended to allow for cell allocations from the pool, prior to initiating the contraction process. In addition, a logic error where subsequent contractions may fail to correctly occur has also been corrected. 100Y CSQSQC64
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
PM95003
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
2013-08-13
Closed date
2013-11-29
Last modified date
2014-01-02
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI13094
Modules/Macros
CSQSQC64
Fix information
Fixed component name
WMQ Z/OS V7
Fixed component ID
5655R3600
Applicable component levels
R100 PSY UI13094
UP13/12/24 P F312
Fix is available
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Document Information
Modified date:
02 January 2014