The user exit programming interface provides global user exit programs
with access to some CICS® services. It consists of a set of macro function calls
that you can use in your user exit programs. It provides opportunities to
extend CICS functions beyond the facilities provided in the standard CICS system, but
it must be used with care. Any exit programs you write that use the interface
must be written following the guidance in this section, and they must be
carefully tested to ensure that they cannot cause system errors.
The user exit programs must be in assembler language; the XPI is not provided
for other languages. You should also note that programs containing XPI calls
must be written to 31-bit standards, and must be reentrant.
You must be in primary-space translation mode when you invoke the XPI.
(For information about translation modes, see the IBM® ESA/370 Principles of Operation manual.)
- Using the XPI dispatcher functions, you can:
- Using the XPI dump control functions, you can:
- Using the XPI enqueue domain functions, you can:
- Using the XPI kernel domain functions, you can:
- Using the XPI loader functions, you can:
- Using the XPI log manager functions, you can:
- Using the XPI monitoring functions, you can:
- Using the XPI program management functions, you
can:
- Using the XPI state data access functions, you can:
- Using the XPI storage control functions, you can:
- Using the XPI trace control function, you can:
- Using the XPI transaction management functions,
you can:
- Using the XPI user journaling function, you can:
Important
- You cannot use all of the XPI calls at every global user exit point. You
will find an indication of when these calls cannot be
used both with the description of each function call, and in the lists of
exit points in Global user exit programs.
XPI calls are used to invoke CICS services; using them in the wrong exits causes unpredictable errors
in your CICS system.
- There is a restriction on using the XPI early during initialization. Do
not start exit programs that use the XPI functions INQUIRE_MONITOR_DATA, MONITOR,
TRANSACTION_DUMP, and WRITE_JOURNAL_DATA until the second phase of the PLTPI.
For further information about the PLTPI, refer to Writing initialization and shutdown programs.
- These XPI functions are likely to cause the task executing the user exit
program to lose control to another task while the XPI function is being executed.
Therefore the use of XPI functions must be very carefully considered, as interrupting
the flow of CICS functions could cause problems, such as lockouts, to occur.

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