A fix is available
APAR status
Closed as program error.
Error description
When a CICS task first uses MQ from Java code an IFAUSAGE REGISTER call is made on the T8 TCB. At the end of the task an IFAUSAGE DEREGISTER call is made. However, this will be made on QR or an L8 and will never be made on the original T8 TCB. The IFAUSAGE DEREGISTER call returns an error, due to being issued on the wrong TCB, and leaves the original IFAUSAGE registration block associated with the T8 TCB. Over time these blocks can mount up leading to a performance issue when future IFAUSAGE calls are made on that T8 TCB.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All CICS users. * **************************************************************** * PROBLEM DESCRIPTION: Build up of IFAUSAGE registration * * blocks due to IFAUSAGE DEREGISTER calls * * being issued on a different TCB to the * * one that issued the REGISTER call. * **************************************************************** A switch environment call allows a TRUE to dissociate any state from an open TCB when it switches between application environments, such as a Java environment, an xplink C environment or a regular non xplink, non Java environment such as traditional Cobol, PLI, or assembler. When the CICS-MQ Attach was enhanced to run on any key 8 TCB, it was thought that expressing interest in switch environment calls was not required because there is no state associated with the TCB that needed to be dereferenced. This was incorrect as use of IFAUSAGE creates such an affinity. When a CICS transaction first uses MQ from Java code an IFAUSAGE REGISTER call is made on the T8 TCB. At the end of the task an IFAUSAGE DEREGISTER call is made. However, this will be made on the QR or an L8 TCB and will never be made on the original T8 TCB. The IFAUSAGE DEREGISTER call returns an error, due to being issued on the wrong TCB, and leaves the original IFAUSAGE registration block associated with the T8 TCB. Over time these blocks can mount up leading to a performance issue when future IFAUSAGE calls are made on that T8 TCB.
Problem conclusion
DFHMQTRU will now express interest in switch application environment events. When called for switch application environment it issues a new SPISWITCH call to MQ. This in turn issues the IFAUSAGE calls. This APAR requires the changes from MQ APAR PH23416 to be effective. MQ APAR PH23416 provides support for the SPISWITCH call. If this APAR is not applied the new function will be called but it will have no effect. With the MQ APAR applied, IFAUSAGE is called when MQ is called for SPISWITCH. This ensures that IFAUSAGE-related control blocks are not retained indefinitely for the T8 TCB.
Temporary fix
Comments
×**** PE21/06/03 FIX IN ERROR. SEE APAR PH37824 FOR DESCRIPTION
APAR Information
APAR number
PH27736
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
2020-07-22
Closed date
2020-08-27
Last modified date
2021-07-16
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI71284 UI71285 UI71286
Modules/Macros
DFHEIQMQ DFHMQAEX DFHMQATB DFHMQBAS DFHMQBR9 DFHMQCOD DFHMQCON DFHMQCTL DFHMQDIS DFHMQDSC DFHMQDSL DFHMQIG DFHMQIN1 DFHMQMNS DFHMQMON DFHMQPOP DFHMQPRM DFHMQPUL DFHMQQCN DFHMQRET DFHMQRP DFHMQRS DFHMQSSQ DFHMQSTB DFHMQTM DFHMQTRC DFHMQTRD DFHMQTRI DFHMQTRQ DFHMQTRU DFHMQTSK DFHMQXCR DFHMQXTB
Fix information
Fixed component name
CICS TS Z/OS V5
Fixed component ID
5655Y0400
Applicable component levels
R100 PSY UI71286
UP20/08/28 P F008
R200 PSY UI71285
UP20/08/28 P F008
R300 PSY UI71284
UP20/09/09 P F009
Fix is available
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[{"Line of Business":{"code":"LOB35","label":"Mainframe SW"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSGMGV","label":"CICS Transaction Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"5.4"}]
Document Information
Modified date:
18 July 2021