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Note: A pseudo-terminal:
– Must be a surrogate TCTTE that exists only in an AOR
– Can be used only in a transaction routing environment
– Cannot exist with distributed program link (DPL) requests
– Cannot exist with any type of function shipping request
– Cannot exist in a distributed transaction.
v PLTPI programs can request services that could suspend the issuing task, but
note that this affects the time at which control is given to CICS. The SUSPEND
must not require the decision to resume to be taken by another task.
v Although PLTPI programs can issue interval control START commands, the
requested transactions are not attached before the initialization stages have
completed, unless the ATTACH option is specified. START ATTACH allows a
START command issued in a PLTPI program to take effect before initialization
has completed. If you use START without the ATTACH option, the transaction
invoked does not start until after the PLTPI programs have completed.
v PLTPI programs must not issue dump requests.
v PLTPI programs must not use the EXEC CICS PERFORM SHUTDOWN
command, or a severe error will occur in DFHDMDM. The EXEC CICS
PERFORM SHUTDOWN IMMEDIATE command is allowed.
v Second stage initialization and second stage quiesce PLT programs do not
require program resource definitions. If they are not defined, they are system
autoinstalled (irrespective of the program autoinstall system initialization
parameters). This means that the autoinstall exit is not called to allow the
definition to be modified. The programs are defined with the following attributes:
LANGUAGE(ASSEMBLER)
STATUS(ENABLED)
CEDF(NO)
DATALOCATION(BELOW)
EXECKEY(CICS)
EXECUTIONSET(FULLAPI)
As a result, system autoinstalled programs have a default CONCURRENCY
setting of QUASIRENT, and a default API setting of CICSAPI.
– For those threadsafe PLT programs that
- are defined with the OPENAPI value for the API attribute, or
- are C or C++ programs compiled with the XPLINK compiler option
provide an appropriate resource definition, or alternatively, for Language
Environment conforming programs, use the CICSVAR runtime option to set
the appropriate CONCURRENCY and API values. See Defining runtime
options for Language Environment, in the CICS Application Programming
Guide.
v You cannot use Debug Tool to debug a second phase PLT program.
Effect of delayed recovery on PLTPI processing
Because recovery processing does not take place until PLTPI processing is
complete, PLT programs may fail during an emergency restart if they attempt to
access resources protected by retained locks. If PLT programs are not written to
handle the LOCKED exception condition, they abend with an AEX8 abend code.
If successful completion of PLTPI processing is essential before your CICS
applications are allowed to start, consider alternative methods of completing
necessary PLT processing. You may have to allow emergency restart recovery
processing to finish, and then complete the failed PLTPI processing when the locks
have been released.
Chapter 4. Writing initialization and shutdown programs 427
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