A fix is available
APAR status
Closed as program error.
Error description
The abend occurs because the ACE on the chain had been freed wi hout being removed from the VLCAAACE chain. APAR PH44903 was previously raised to detect an ACE being freed while still on a VLCAAACE chain, but clearly it hasn't worked in this case. However, in reviewing the code in this area, there i s a scenario where the change from APAR PH44903 wouldn't catch t his problem. This APAR was raised to enhance the diagnostic checks added by A PAR PH44903.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM MQ for z/OS Version 9 * * Release 4 Modification 0 * **************************************************************** * PROBLEM DESCRIPTION: Various symptoms may be observed due to * * an ACE being freed whilst still being * * on a VLCAAACE chain * * * * Symptoms can include: * * 0C4 abends * * 60D abends * **************************************************************** Code does not do sufficient checking when adding an ACE to a VLCAAACE chain, allowing an ACE to be added to multiple chains.
Problem conclusion
Checks have been added to ensure an ACE is not added to a VLCAAACE chain multiple times, or to multiple VLCAACE chains. Additional diagnostic abend 5C6-00E5003A has been added to take an SVC dump when this check fails.
Temporary fix
Comments
APAR Information
APAR number
PH65668
Reported component name
IBM MQ Z/OS V9
Reported component ID
5655MQ900
Reported release
300
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2025-03-15
Closed date
2026-03-26
Last modified date
2026-05-02
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UO07285 UO07286
Modules/Macros
CSQ3RRSF CSQ3RRSM CSQMCPRH CSQMCTXE CSQVASTM CSQVCONN CSQVCRTH
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:
02 May 2026