A fix is available
APAR status
Closed as program error.
Error description
You have several tasks in LMQUEUE suspends waiting on the XMATTLCK lock. Normal attaches hold the XMATTLCK shared and new threading model for Liberty is designed to request the XMATTLCK exclusive. This is causing a deadlock with the task needing the exclusive not getting it until all the shared tasks finish.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All CICS users. * **************************************************************** * PROBLEM DESCRIPTION: Deadlock for XMATTLCK leads to * * no transactions being attached * * for two minutes. * **************************************************************** A CICS system is configured to accept work over MRO, and also through a Liberty JVM server running in the region. A routed transaction arrives and starts processing the attach for a new task. This task becomes a holder of the shared XMATTLCK. The transaction was routed over MRO, so begins to run the DFHMRXM primary client initialisation (INIT_XM_CLIENT) routine. Meanwhile, a web request arrives in a Liberty JVM server. A new task must be built for this request (using BUILD_TRANSACTION) and this new task requests the XMATTLCK as an exclusive lock. The original MRO task, still holding the XMATTLCK as a shared lock, then needs to attach a CITS task. This new CITS also needs to become an owner of the shared XMATTLCK, but cannot now do so due to the outstanding exclusive request for this same lock. This system is now deadlocked, and no transaction can be attached until a timeout occurs on the MRO task. This takes approximately two minutes. The original routing transaction will abend AZI6. . Additional Keywords: abendAZI6 abendAZTB abendAZVA AZTB AZVA msgDFHAC2236 DFHAC2236
Problem conclusion
The CICS transaction attach mechanism has been updated to avoid the potential for this deadlock while initialising the primary client.
Temporary fix
Comments
APAR Information
APAR number
PI95725
Reported component name
CICS TS Z/OS V5
Reported component ID
5655Y0400
Reported release
100
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2018-03-26
Closed date
2018-04-27
Last modified date
2018-05-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI55546
Modules/Macros
DFHXMTA
Fix information
Fixed component name
CICS TS Z/OS V5
Fixed component ID
5655Y0400
Applicable component levels
R100 PSY UI55546
UP18/04/28 P F804
Fix is available
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Document Information
Modified date:
01 May 2018