A fix is available
APAR status
Closed as program error.
Error description
CICS region hung due to a loop in DFHSOST that occurred while processing end-of-day statistics for the Sockets domain. The loop occurs on the QR TCB while running under a Timer task. . MVS system trace shows that the loop is in DFHSOST (label TCPIP_GET_NEXT_STATS_RECORD, range x'A62' through x'1C50'). The loop is occuring because of an invalid browse token. The statistics loop in DFHSOST is only expecting the browse/getnext loop to end with an end_browse, not an invalid token. So it only checks for RC4 (tcpips_end_browse) and then doesn't break out of the loop. . The invalid browse token occurred when a task doing an INQUIRE TCPIPSERVICE request ran at the same time as the Timer task collecting sockets domain statistics. The Timer task did a start_browse first, and did a GETMAIN for it's browse element (subpool SOTBR). It then suspended. The INQUIRE TCPIPSERVICE task then did it's start_browse. During this start_browse, housekeeping code in DFHSOST freemains the browse element out from under the Timer task (this housekeeping code uses DFHXMIQ calls but XM domain does not know about the Timer task). This task then does a GETMAIN and gets the just-freed browse token, and will eventually free it again during it's tcpips_end_browse processing. . The Timer task now runs again, but the browse token has been freed out from under it so it gets the invalid_browse_token response and the loop begins. . Additional Symptom(s) Search Keyword(s): KIXREVSLY tcpips_invalid_browse_token
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All CICS users. * **************************************************************** * PROBLEM DESCRIPTION: Endless loop happens on QR when * * processing end-of-day statistics * * from SO domain. * **************************************************************** * RECOMMENDATION: * **************************************************************** The timer task is running for end of day statistics. DFHSOST is called to get the statistics from sockets domain. DFHSOST obtains the TCPIPSERVICE lock exclusively, GETMAINs a browse token and then issues a browse loop to gather the statistics information for each TCPIPSERVICE. The browse loop continues until the statistics buffer is full. DFHSOST releases the lock, processes the buffer and then relinquishes the QR. At this point, another task gets to run on the QR. That task needs to browse TCPIPSERVICEs. It gets the exclusive lock and then start the browse. Before it gets the browse token, CICS does some cleanup first. The cleanup code attempts to free the unused browse tokens. The token for timer task is detected. Since the timer task is not know to transaction manager, CICS believes that token is unused and frees it. When timer task gets dispatched again. It re-acquires the exclusive lock and loops round to continue the statistics. As its browse token is freed, DFHSOST gets the invalid browse token exception each time in the browse loop. Since the browse loop is only terminated by reaching the end, the endless loop happens.
Problem conclusion
DFHSOST and DFHSOTD have been changed so that the cleanup code does not attempt to delete the timer task browse token.
Temporary fix
********* * HIPER * ********* FIX AVAILABLE BY PTF ONLY
Comments
APAR Information
APAR number
PM82467
Reported component name
CICS TS Z/OS V4
Reported component ID
5655S9700
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt
Submitted date
2013-02-08
Closed date
2013-03-19
Last modified date
2013-04-02
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
PM83413 UK92742
Modules/Macros
DFHSOAD DFHSOCK DFHSODM DFHSODUF DFHSOIS DFHSOLS DFHSOST DFHSOTB
Fix information
Fixed component name
CICS TS Z/OS V4
Fixed component ID
5655S9700
Applicable component levels
R700 PSY UK92742
UP13/03/29 P F303
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:
02 April 2013