A fix is available
APAR status
Closed as unreproducible.
Error description
Customer forces TCPIP down via a CEMT SET TCPIP CLOSED command. Then he issues a CEMT IN IPCONN which results in the CEMT task getting stuck in a LMQUEUE wait for shared ISCB lock. The problem is caused by the CIST task that hold the ISCB chain lock and a SHARED lock on the IPCONN. Because the IPCONN has been autoinstalled, CIST calls DFHISIC DISCARD_IPCONN. During that process an attempt to acquire an EXCLUSIVE LOCK result in the task being suspended because there is a SHARED LOCK already own by a task. The SHARED LOCK happen to be own by the same task, CIST. CIST will never get resumed now. When the CEMT I IPCONN is issued it need a SHARED lock of the ISCB chain which has an EXCLUSIVE lock own by CIST. The task is now hung. . Additional Keyword(s) and Symptom(s): KIXREVSVR
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All * **************************************************************** * PROBLEM DESCRIPTION: CEMT INQUIRE IPCONN hangs after issuing * * CEMT SET TCPIP CLOSED. * **************************************************************** * RECOMMENDATION: * **************************************************************** An IPCONN is autoinstalled when a new IPIC connection is established by a CICS Transaction Gateway ( CTG ) connecting to a TCPIPSERVICE defined with PROTOCOL(IPIC). Later on a CEMT SET TCPIP CLOSED command is issued. This causes a CIST task to be attached for every active IPIC TCPIPSERVICE definition. The CIST task loops through the IPCONN directory and attempts to terminate all IPCONNs associated with the selected TCPIPSERVICE. DFHISCO obtains a shared lock manager lock on the selected IPCONN then calls DFHISEM for FUNCTION PURGE_IPCONN. DFHISEM eventually calls DFHISIC for function DISCARD_IPCONN. DFHISIC has to obtain an exclusive lock on the IPCONN before discarding it. This request hangs as an exclusive lock cannot be obtained while a shared lock is still held. The CIST task will hang indefinitely with an outstanding request to obtain the exclusive lock. The same problem occurs if a CEMT SET TCPIPSERVICE IMMCLOSE command is issued against an IPIC TCPIPSERVICE. If a CEMT INQUIRE IPCONN command is now issued this will hang as it cannot obtain a shared lock on the IPCONN while there is an exclusive lock request still outstanding. ADDITIONAL KEYWORDS :- LMQUEUE
Problem conclusion
Temporary fix
********* * HIPER * ********* FIX AVAILABLE BY PTF ONLY
Comments
The PURGE_IPCONN logic in DFHISEM has been changed to ensure that the shared lock on the IPCONN is released before the IPCONN is discarded. DFHISCO has been changed to avoid releasing the IPCONN lock after calling DFHISEM for function PURGE_IPCONN.
APAR Information
APAR number
PK85091
Reported component name
CICSTS V3 Z/OS
Reported component ID
5655M1500
Reported release
500
Status
CLOSED UR3
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt
Submitted date
2009-04-21
Closed date
2009-07-06
Last modified date
2009-08-03
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
PK89455 UK48138
Modules/Macros
DESISCO DESISEM DFHISCO DFHISCOA DFHISCOM DFHISCOP DFHISCOT DFHISEM
Fix information
Fixed component name
CICSTS V3 Z/OS
Fixed component ID
5655M1500
Applicable component levels
R500 PSY UK48138
UP09/07/11 P F907
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:
03 August 2009