A fix is available
APAR status
Closed as program error.
Error description
The customer is running WebSphere MQ V7.1 and they are receiving the 5C6-00E2000B. This has occurred due to the queue- manager going short on storage due to the problem with the ITRQP control blocks associated with a specific queue. These ITRQP control blocks should only be present when commits are performed while an MQGET is in-progress. However, it looks as though IVSA.lGetCursCnt is set to 1 although there are actually no in-progress MQGETs. . From the dump the change team can see that a very large proportion of these ITRQP control blocks have been incorrectly built. That is, the RPR of the message that they relate to should be in ITRQP_CRPR but the control blocks actually contain an address (also ITRQP_CSTCK should contain the STCK of the message, but it is 0). the Change team can see that this problem with the control blocks being incorrectly built could occur if there is a problem during MQPUT processing, for instance if the application passed an invalid buffer address, resulting in MQRC 2004, MQRC_BUFFER_ERROR, which is the reason for the incorrectly-built ITRQP control blocks. . The change team has not been able to determine why these control blocks have not been released though (which lead to the short-on-storage experienced by the QMGR). We are taking this APAR so that the change team can investigate further how these incorrect ITRQP control blocks can go unreleased.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 * * Release 1 Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: Build up of invalid ITRQP control * * blocks occurs following failing MQPUT * * calls, leading to increased get/browse * * times and storage shortages in the * * queue manager address space. * **************************************************************** * RECOMMENDATION: * **************************************************************** An application attempting to put a message to a queue fails (for example, due to CSQI_PAGESET_FULL) and rel_locks is called to release any request locks obtained during the failing MQPUT. If the queue being put to is also being processed by any MQGET calls, an ITRQP is incorrectly queued to the IVSA for the queue by rel_locks. The invalid ITRQP causes any in progress MQGETs to restart scanning the page chain, delaying completion of the MQGET request. The invalid ITRQPs will be freed when the last MQGET using them completes. In some cases the page chain rescans caused by the invalid ITRQPs can delay the MQGET request long enough for further invalid ITRQPs to be created, resulting in additional rescans, and delays the freeing of the invalid blocks. This can lead to the storage used by the ITRQP pool growing and potentially leading to a short on storage condition and abends relating to insufficient available storages e.g. S878
Problem conclusion
CSQIMPU2 is changed to no longer queue an invalid ITRQP to the IVSA chain following a failing MQPUT. 100Y CSQIMPU2
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
PI14456
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
2014-03-25
Closed date
2014-06-20
Last modified date
2014-08-04
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI19014
Modules/Macros
CSQIMPU2
Fix information
Fixed component name
WMQ Z/OS V7
Fixed component ID
5655R3600
Applicable component levels
R100 PSY UI19014
UP14/07/22 P F407 ¢
Fix is available
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Document Information
Modified date:
04 August 2014