A fix is available
APAR status
Closed as program error.
Error description
After WebSphere MQ 7.1.0 PTF UI11931 for APAR PM90755 and z/OS Recovery Termination Management (RTM) APAR OA46028 are applied, an overlay can occur of the TCBMSS field for the IMS TCB for DFSPCC20. Because of the TCBMSS overlay, Virtual Storage Manager (VSM) control block VSWKDQE may end up with a non-zero value which does not point to a valid DQE. This results in an ABEND0C4 in IGVFSDQE JBB778H +x'1AA' because storage pointed to by Reg6 is not available. This module is involved in doing subpool freemains. The CSQQSSON code that caused the overlay is using Reg11 without initializing it, and R11 is not an interface register between RTM and resource managers. Prior to the code change introduced by APAR OA46028, Reg11 residually pointed to an STCB when CSQQSSON was invoked. Therefore, the overlay was to STCB+18 which happens to be a reserved field and therefore did no harm. However, after the OA46028 code change, Reg11 happened to residually point to a TCB when CSQQSSON was invoked. Therefore, the overlay was to TCB+18, the TCBMSS field, leading to downstream effects on VSM processing. This problem is only evident in the UI11931 version of CSQQSSON. Note that an overlay may still occur without the PTF for OA46028 applied. The exact symtpoms that this overlay may cause are unpredictable. Additional Symptom(s) Search Keyword(s): Follow-on symptoms in IMS may include: - ABENDB78 ABENDSB78 B78 SB78 S0B78 RC4 4 00000004 B78-04 The freemain failed because R8 has been loaded from the TCBMSS field, which should be a Subpool Queue Element (SPQE)address. - ABEND378 ABENDS378 378 S378 S0378 RC14 14 00000014 378-14 - IMS MPP region hangs or has high CPU after /STO REGION is issued. hang hung hanging performance - IPCS VSMDATA in a dump reports possible storage overlays: => FBQE Area Address is invalid - possible storage overlay ABEND0C4 ABENDS0C4 0C4 S0C4 S00C4 CSQQWait_Termination
Local fix
Back out MQ APAR PM90755 or RTM APAR OA46028 - Also, a ++APAR is available from the MQ support team.
Problem summary
**************************************************************** * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 * * Release 1 Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: CSQQSSON overlays 4 bytes of system * * storage when an IMS MPP terminates * * following application of PM90755 * * (UI11931). * * Following application of OA46028 * * (UA75442/UA75443) this overlay * * leads to abend0c4 errors in VSM * * modules during IMS MPP termination * * as described by OA47064. * **************************************************************** * RECOMMENDATION: * **************************************************************** During termination of an IMS MPP that has connected to a queue manager, CSQQSSON's RESMGR routine is called. Following application of UI11931 this routine incorrectly overlays 4 bytes of storage at R11+x18. Prior to OA46028 the contents of R11 on entry to the resmgr routine meant that the overlaid storage was unused, and consequently no errors occurred. However, following application of OA46028 the contents of R11 on entry to the resmgr routine have changed, and R11+x18 contains the address of a VSM control block. The overlay prevents VSM routines locating this control block correctly, leading to abend 0C4 errors.
Problem conclusion
CSQQSSON is changed to prevent it overlaying storage using R11. 100Y CSQQSSON CSQQTMID CSQQTTHD
Temporary fix
Comments
APAR Information
APAR number
PI34742
Reported component name
WMQ Z/OS V7
Reported component ID
5655R3600
Reported release
100
Status
CLOSED PER
PE
YesPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2015-02-10
Closed date
2015-03-03
Last modified date
2015-05-06
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI25577
Modules/Macros
CSQQSSON CSQQTMID CSQQTTHD
Fix information
Fixed component name
WMQ Z/OS V7
Fixed component ID
5655R3600
Applicable component levels
R100 PSY UI25577
UP15/04/17 P F504 {
Fix is available
Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
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Document Information
Modified date:
06 May 2015