A fix is available
APAR status
Closed as program error.
Error description
An abend in a MAS is possible if, during or after a CMAS shutdown, a MAS attempts to access or update control blocks that the CMAS has already FREEMAINed. It may happen during a small timing window if the MAS is starting and trying to connect to the CMAS at the same time that the CMAS is shutting down, but it may also happen at other times. . In the MAS job log, you will see a method list similar to the following: . EYUXL0905E Methods=CTUS,CTBT,CTBP,CAMS,XMSM,NLRA,XLOP . In the dump, the PSW in the exception trace for the abend places us in method CTUS / EYU0CTUS and we are attempting to access a field in the CLCB. In the case for which this APAR was opened, that field was CLCB_SCHED_CLOCK, but since the CMAS shutdown has already freed the CLCB ( link conversation block ) then this field is no longer valid. . If the storage location has been reused already, this may cause an abend, depending on the storage contents. If an abend does not immediately occur, the storage could become corrupt. . . Additional Symptom(s) Search Keyword(s): KIXREVSVR
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All CICSPlex SM V5R2M0 and V5R3M0 Users * **************************************************************** * PROBLEM DESCRIPTION: When you bring up a MAS region during * * the termination of CMAS region that the * * MAS region is connected to, you may * * experience S0C4 abend in method CTUS. * **************************************************************** * RECOMMENDATION: After applying the PTF that resolves this * * APAR, all CMASes and MASes must be * * restarted. Note that the restarts do not * * need to occur at the same time. * **************************************************************** For CMAS to MAS and CMAS to CMAS communications, method EYU0CTUS (CTUS - Communication Transport Services Update Statistics) is called by a number of methods to update the link statistics of either the send or receive session. CTUS relies on LCNVB (Link Conversation Block) that is passed by the callers to reference the statistics area. When the CMAS region is terminated, method EYU0CLET (COMM LPROT ESSS Initial Contact Transient) is driven to release the control blocks allocated for CMAS to MAS communications, including LCNVBs. Therefore, when a MAS region is started during the termination of CMAS region that the MAS region is connected to, the LCNVB that CTUS gets from the callers could have been released by CLET, and subsequently been overwritten by other methods. In that case, method CTUS uses invalid LCNVB to reference the statistics area, and S0C4 abend occurs if the data is non-accessible.
Problem conclusion
Method EYU0CTUS has been updated to check existence of the CMAS region before using LCNVB passed from the callers.
Temporary fix
Comments
APAR Information
APAR number
PI77845
Reported component name
CICS TS Z/OS V5
Reported component ID
5655Y0400
Reported release
90M
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2017-03-08
Closed date
2017-04-21
Last modified date
2017-05-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI46632 UI46633
Modules/Macros
EYU0CTUS
Fix information
Fixed component name
CICS TS Z/OS V5
Fixed component ID
5655Y0400
Applicable component levels
Fix is available
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Document Information
Modified date:
01 May 2017