The following steps describe basic application execution under CICS®:
- An event, generally the receipt of an input message containing
a transaction ID code, triggers a Language Environment process
(CICS transaction).
- CICS looks up the transaction
ID code in the program control table (PCT) and gets the name of the
enclave (or the first
enclave) to execute the process.
- CICS defines the process
(transaction) as a work item that is dispatched by the CICS task dispatcher.
- After the process is defined, CICS looks
up the identity of the enclave required to perform the task in the
processing program table (PPT). The PPT contains information about
the enclave such as its language, whether it is in
storage, and if in storage, its use count and entry point address.
- CICS calls the Language Environment-CICS
runtime level interface to initialize the process-related portions
of the runtime environment.
- If the enclave does not perform all the processing associated
with the process, the enclave might pass control to another enclave
through a language call or through the EXEC CICS LINK or EXEC CICS XCTL
commands.
- When the process is complete, CICS calls
the Language Environment-CICS
runtime level interface to terminate the process-related portions
of the runtime environment.
- IEEE binary and decimal floating-point are supported in a CICS environment only if CICS 4.1 or later is in use.