A fix is available
APAR status
Closed as program error.
Error description
Transactions may enter FCDWSUSP waits and never exit. This can occur when heavy insert activity takes place on the KSDS Base Cluster while heavy read activity take place on the Paths. The AIX and the Base records may temporarily get out of sync and the FCDWSUSP wait is used to temporarily delay requests until the Base and Paths can be brought into sync. The FCDWSUSPs sould only last for a very short time. There are times when the sync process can be interrupted and the fctbc_0890_count along with the vswa_0890_post can become out of sync. The end result will show up as transactions stuck in FCDWSUSP waits. These waits should be very temporary.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All * **************************************************************** * PROBLEM DESCRIPTION: Transactions stuck in FCDWSUSP * * waits indefinitely. * **************************************************************** * RECOMMENDATION: * **************************************************************** Transactions may enter FCDWSUSP waits and never exit them. This can occur when heavy insert activity takes place on the KSDS base cluster while heavy read activity take place on its paths. The AIX (alternative index) and the base records may temporarily get out of step with respect to each other within VSAM, and the FCDWSUSP suspend is used to temporarily delay requests until the base and paths are synchronized again. These suspends are driven when VSAM returns an 0890 error, to indicate that the record being read is not present in the path. FCDWSUSP suspends should only last a short time, as when the update set work to complete the record insertion has completed, the record being read via the path should then be available. If a VSAM request experiences an exclusive control conflict, CICS calls routine ADDVSWA to process the VSWA for the request. Part of this involves freeing any VSAM resources before suspending the task. DFHFCVS preserves the content of vswa_0890_post around this call. This flag (if set on) means that the VSWA represents a request that may have led to an 0890 being returned to a reader of the file. There is a corresponding count of such requestors maintained in the FCT (fctbc_0890_count). The intention is that when requests complete, and this count has reduced to 0, the tasks waiting on FCDWSUSP suspends are resumed, and can retry their requests. If FREE_VSAM_RESOURCES causes the value of vswa_0890_post to be changed (either to be set on if another task experiences an 0890, or set off, and the count decrement, if it had been on) then the restoration of the flag to its previous value when control returns to ADDVSWA will leave the flag and count in an inconsistent state. The count may now be 0 yet the bit still on, or the count now be 1 yet the bit off. Either way, the logic will not resume the tasks suspended on FCDWSUSP, and they will remain in the system indefinitely.
Problem conclusion
UK37688 UK47823 DFHFCVS has been changed to no longer save and restore the value of vswa_0890_post around the call to FREE_VSAM_RESOURCES.
Temporary fix
FIX AVAILABLE BY PTF ONLY
Comments
APAR Information
APAR number
PM10667
Reported component name
CICSTS V3 Z/OS
Reported component ID
5655M1500
Reported release
500
Status
CLOSED PER
PE
YesPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2010-03-23
Closed date
2010-06-29
Last modified date
2010-08-02
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
PM10588 UK58522
Modules/Macros
DFHFCVS DFHFCVS1
Fix information
Fixed component name
CICSTS V3 Z/OS
Fixed component ID
5655M1500
Applicable component levels
R500 PSY UK58522
UP10/07/09 P F007
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 August 2010