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6.1.9 CICS System Program Interface and Exits
6.1.9.1 System Programming Commands
CICS system programming interface (SPI) commands provide you with the ability
to access and modify CICS system information. SPI should be considered for
CICS applications that presently modify and/or access CICS internal blocks.
Although, SPI commands will not grant access to all CICS blocks and addresses,
SPI commands either retrieve information about CICS resources or system
elements from:
INQUIRE commands
COLLECT STATISTICS
or commands that modify the status or definition of the system or a resource, or
invoke a system process:
SET commands
CREATE commands
DISCARD commands
PERFORM commands
ACQUIRE TERMINAL
or commands that modify or expand system execution by means of exits:
DISABLE PROGRAM
ENABLE PROGRAM
EXTRACT EXIT
RESYNC ENTRYNAME
CICS TS requires that all SPI commands specify an SP translator option and
security checking for transactions issuing SPI commands. Therefore, you should
review all SPI commands of CICS TS to determine what modifications and
reassemblies are required to your present SPI programs. Please refer to
CICS
System Programming Reference
, SC33-1689 for more details on SPI command
changes and the
CICS Application Programming Guide
, SC33-1687 for
information on the translator options.
6.1.9.2 Exits
Exits will require special attention and a significant amount of your conversion
work effort. All exits will require a rewrite.
CICS TS does not support changes to internal control blocks. 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 should be used
with care. Any exit programs you write that use the interface must be written
following the specific guidance documented in the
CICS Customization Guide
,
SC33-1683, and you should carefully test to ensure that they cannot cause
system errors.
The user exit programs must be in Assembler; 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.
Chapter 6. CICS 147