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user exit should invoke its resource manager to free any task-related
resources, such as the thread. However, the resource manager should
maintain any locks held by the UOW, and record that the UOW is in-doubt.
When CICS receives the outcome of the UOW from its coordinator, a
resynchronization task is attached to notify the task-related user exit about
the outcome of the UOW.
If CICS is in-doubt about the outcome of a UOW for which an external
resource manager has requested resynchronization (using the EXEC CICS
RESYNC command), CICS waits until the in-doubt has been resolved
before initiating a resynchronization task.
The effects of not enabling a task-related user exit with the INDOUBT
keyword are:
v If CICS is in-doubt about a UOW, a forced decision is taken and the
task-related user exit invoked with the forced decision.
v If CICS is forced to take a decision because a task-related user exit is
not enabled with INDOUBTWAIT, it takes a forced decision for all
resources updated by the UOW, even if all the other resources are
capable of waiting for in-doubt resolution. This applies to local resources
such as files, and also other RMCs, such as LU6.1, LU6.2, or MRO
connections to other systems.
v An inbound RESYNC command from a resource manager that requests
resynchronization for a UOW that CICS was in-doubt about, results in
CICS invoking the task-related user exit with a forced decision.
SHUTDOWN
specifies that the exit program is to be invoked at CICS shutdown.
SPI specifies that the exit program is to be invoked to satisfy EXEC CICS
INQUIRE EXITPROGRAM calls that specify the CONNECTST or
QUALIFIER options. Use this option to enable user programs to discover
whether the exit program is connected to its resource manager, and what
its entryname qualifier is.
Note: The exit program can set this option dynamically, by setting the
UEFMSPI bit-mask in the schedule flag word.
For programming information about the EXEC CICS ENABLE PROGRAM
command, refer to the
CICS System Programming Reference
manual.
The administration routines
As well as being enabled before they can be used, task-related user exit programs
should be disabled when you have finished using them. You should prepare
procedures (the administration routines) for enabling and disabling your task-related
user exit programs, using the EXEC CICS ENABLE and DISABLE commands, and
for resynchronizing between sessions or after a system failure. Your enabling
routines could be PLT initialization programs or online programs. Your disabling
routines could, for example, be started by a TRUE invoked at CICS termination.
The EXTRACT EXIT command obtains the address and the length of a global work
area that is owned by, or shared by, a named task-related user exit program.
For programming information about these commands and the rules governing them,
and also about resynchronization, refer to the
CICS System Programming
Reference
manual.
adapter administration
Chapter 2. Task-related user exit programs 281