A fix is available
APAR status
Closed as program error.
Error description
ABEND502 in load module CSQXDISP occurs as space looks to have run out in the z/OS events table for the async consumer notification TCB (ACNO). The ACNO task has been dispatched but is being suspended. If the ACNO task gets busy, the overhead from its storage requests (which are done via MVS STORAGE/OBTAIN release) can cause its TCB to be suspended while waiting on the local lock. During this time ECB events for notification of message arrivals continue to be posted. In this APAR's case it appears that the number of post events has exceeded the ACNO's EVENTS table capacity due to the overhead of the additional STORAGE requests. This results in the EVENTS table reaching its maximum capacity and POST failing with ABEND502.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of WebSphere MQ for z/OS * * Version 7 Release 0 Modification 1 and * * Release 1 Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: Abend S502 may occur when a large * * number of messages arrive for * * waiting SVRCONNs at once. * **************************************************************** * RECOMMENDATION: * **************************************************************** When a very large number of messages arrive for waiting SVRCONN channels with a non-zero SHARECNV value, it is possible under certain circumstances that the processing of the arrival notifications for these messages may result in the events table filling up for the async-consumer notification task. This occurs because the task is performing diagnostic tracing that requires a small amount of automatic storage to be obtained and released for every message that arrives. Because of this overhead, the processing is slowed down and in rare circumstances it is possible for the events table to fill up resulting in an S502 abend.
Problem conclusion
The processing of the async-consumer notification task is amended so that no storage needs to be obtained when tracing. In addition, the dispatch priority of the TCB has been raised and the size of the z/OS events table for the ECBs has been increased. 010Y 100Y CSQXACNO CSQXJST CSQXSFRE CSQXSGET
Temporary fix
Comments
APAR Information
APAR number
PM76990
Reported component name
WMQ Z/OS V7
Reported component ID
5655R3600
Reported release
010
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2012-11-13
Closed date
2012-11-28
Last modified date
2013-02-04
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK83814 UK83815
Modules/Macros
CSQXACNO CSQXJST CSQXSFRE CSQXSGET
Fix information
Fixed component name
WMQ Z/OS V7
Fixed component ID
5655R3600
Applicable component levels
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.
[{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SG19M","label":"APARs - z\/OS environment"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0.1","Edition":"","Line of Business":{"code":"","label":""}}]
Document Information
Modified date:
04 February 2013