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UERCNORM
Resume normal operation of the link or modegroup.
UERCAPUR
Reject the allocate request with SYSIDERR.
XPI calls
All can be used.
Designing an XZIQUE global user exit program
The functions of your XZIQUE exit should be designed:
1. To control of the number of tasks (and the amount of associated resource) that
are waiting in a queue for a free intersystem session. Waiting tasks can degrade
the performance of the local system.
2. To detect poor response from the receiving (remote) system and to notify the
operator (or automatic operations program).
3. To cause CICS to issue a message when the link resumes normal operation.
The XZIQUE global user exit parameter list is designed to support these objectives.
Related concepts
“The MRO and APPC session queue management sample exit program” on page
24
Design considerations: The information passed at XZIQUE is designed to enable
your XZIQUE global user exit program to:
v Avoid false diagnosis of problems on the connection by distinguishing poor
response times from a complete bottleneck
v Ensure that a link resumes normal operation quickly and without operator
intervention once any problem in a remote system is resolved.
Some guidance on the use of IRC/ISC statistics: CICS adds an entry for
unsatisfied allocate requests to the following queues:
Non-specific (generic) allocate queue
All non-specific allocate requests are queued in this single queue. CICS makes
the total number of entries in this queue available in the system entry statistics
field A14ESTAQ, to which your global user exit program has access by means
of the address of the system entry statistics, which is passed in UEPCONST.
Specific modegroup allocate queues
Specific allocate requests are queued in the appropriate modegroup
queue—one queue for each specific modegroup name. CICS makes the total
number of entries in all these queues available, as a single total, in the mode
entry statistics field A20ESTAQ, to which your global user exit program has
access by means of the address of the mode entry statistics, which is passed in
UEPMODST.
Sample exit program design: A sample XZIQUE exit program is provided with
CICS Transaction Server for z/OS, Version 3 Release 2 as a base for you to design
your own global user exit program. It is called DFH$XZIQ, and is supplied in the
CICSTS32.CICS.SDFHSAMP library. The DSECT used by the sample program to
map the area addressed by UEPZDATA is called DFHXZIDS, and this is supplied in
the CICSTS32.CICS.SDFHMAC library.
As supplied, the sample exit program implements the same basic function as
described for the QUEUELIMIT and MAXQTIME parameters on the connection
resource definition. If the XZIQUE exit is not enabled, CICS uses these parameters
256 Customization Guide