A fix is available
APAR status
Closed as program error.
Error description
A 5C6-00E2000C abend occurred during an attempt to get ECSA storage. As ACELIM was configured, CSQY228E ACELIM REACHED also occurred. The MQ MSTR job was one of the high users of ECSA due high usage of MQ thread-related subpools such as RAL, "ccb for ssam", "conn,agnt,fvl+others", ROB, and ACE/PEB. There was a buildup of MMCLTRX system threads. These tasks were all waiting to obtain a latch. The latch holder was waiting for a latch that was held by a thread for an application job. The application job had received an earlier ABEND07D RC0 (Functional Recovery Routine (FRR) stack full), which was followed by an ABEND S0DC - REASON CODE 08 to request a MEMTERM of the address space. A thread in the address space still held a latch. z/OS APAR OA62248 assists in obtaining documentation for the ABEND0DC. MQ development has been able to recreate the problem whereby a task with an FRR stack depth of 7 calls MQ for RRS commit processing and subsequently abends S07D. This APAR is to investigate how best to address this problem.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM MQ for z/OS Version 9 * * Release 2 Modification 0 and * * Release 3 Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: An 07D-00 abend is seen in the Queue * * Manager address space leading to an * * 0DC-08 memterm being scheduled for the * * connected application address space. * **************************************************************** An 07D-00 abend is seen in the Queue Manager address space due to a failed attempt to add an additional FRR to a full FRR stack. This leads to a 0DC-08 memterm being scheduled for the connected application address space. The FRR stack was unusually full due to a series of rare code paths all being traversed on the same task. In this case the FRR stack held entries from DB2 stored procedures, RRS commit processing, MQ Logging processing, a checkpoint being initiated due to LOGLOAD being hit and latch contention.
Problem conclusion
The code has been altered so that additional FRR entries are not required as part of initiating a checkpoint when Logload has been hit. This has the affect of reducing the current depth of the FRR stack avoiding the reported symptoms of this APAR. Additionally a back stop abend 5C6-00E513A1 has been introduced to prevent attempts to add an FFR to the FRR stack when there is not enough space to do so. This will help identify other potential paths to reach the symptoms described by this APAR. Instead of an application address space being memtermed this new abend will be issued and a dump produced that can be given to IBM support for analysis.
Temporary fix
Comments
APAR Information
APAR number
PH50082
Reported component name
IBM MQ Z/OS V9
Reported component ID
5655MQ900
Reported release
200
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2022-10-10
Closed date
2023-11-06
Last modified date
2023-12-02
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI94305 UI94306
Modules/Macros
CSQRCRQS CSQRCRSC CSQRCSHT CSQRIT01 CSQVSRX
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:
04 December 2023