A fix is available
APAR status
Closed as program error.
Error description
There is a threadsafe program that makes some SQL calls and lots of File Control calls to a file that is a shared data table. Being a shared data table, CICS must be on the QR TCB to process the request. (The same would be true of an NSR file and also, if not z/OS 1.9 or higher, LSR files.) Since migrating to CICS/TS 3.2, this program uses more CPU and has lots more TCB switches than it did at a prior release of CICS.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All * **************************************************************** * PROBLEM DESCRIPTION: Response time degradation when * * threadsafe applications repeatedly call * * file control. * **************************************************************** * RECOMMENDATION: * **************************************************************** A threadsafe (but not openapi) program called DB2 and so was switched to an L8 TCB. It then called file control. The file was defined as a shared data table, and such requests are not threadsafe to CICS. This meant that DFHFCFR had to switch to QR for the duration of the request. However, it then switched back to the caller's old TCB mode upon exit from DFHFCFR. For many such calls to file control, the application was being switched from L8 to QR and back to L8 again. This led to an increase in CPU usage, and a rise in response time for the application to complete. Note: the same problem applies to other types of file which require the use of QR, such as BDAM files and remote files. Keywords: SDT CICSPERF performance PK45354
Problem conclusion
DFHFCFR routine ACCMTEST has been changed to avoid switches back to the caller's TCB mode upon completion of the request, if the caller was a threadsafe CICSAPI program that did not require to be executed under an open TCB. This brings file control into line with other parts of CICS that have to switch to the QR TCB to process non-threadsafe EXEC CICS commands.
Temporary fix
FIX AVAILABLE BY PTF ONLY
Comments
APAR Information
APAR number
PK70646
Reported component name
CICSTS V3 Z/OS
Reported component ID
5655M1500
Reported release
500
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2008-08-15
Closed date
2008-10-16
Last modified date
2008-11-03
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK40779
Modules/Macros
DESFCCM DFHFCCMS DFHFCDMS DFHFCFR DFHFCLMS
Fix information
Fixed component name
CICSTS V3 Z/OS
Fixed component ID
5655M1500
Applicable component levels
R500 PSY UK40779
UP08/10/21 P F810
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 November 2008