The EXCI EXEC CICS interface

The EXCI EXEC CICS interface provides several commands. For example, the interface provides a single, composite command, EXEC CICS LINK PROGRAM command, that performs all six commands of the EXCI CALL interface in one invocation. Each time you issue an EXEC CICS LINK PROGRAM command in a client application program, the external CICS® interface invokes each of the six EXCI calls on your behalf. The EXEC CICS LINK PROGRAM command is similar but not identical to the distributed program link command of the CICS command-level application programming interface.

EXCI also provides the ability to process data using channel and container commands. A channel together with its set of containers can then be passed on the EXEC CICS LINK PROGRAM command or on a call API DPL_REQUEST, as an alternative to using a communications area to transfer data or information from one program to another.

Illustration of the EXCI EXEC CICS interface

This diagram illustrates the EXEC CICS interface, and how it resolves to the six EXCI CALLs.

Figure 1. Illustration of the external CICS interface using the EXEC CICS command
This diagram shows the z/OS Client Application issuing an EXEC CICS LINK command. The EXEC interface stub DFHXCSTB calls the EXCI EXEC interface program which issues the following calls: INITIALIZE_USER, ALLOCATE_PIPE, OPEN_PIPE, DPL, CLOSE_PIPE, DEALLOCATE_PIPE
  1. The z/OS® Client Application issues an EXEC CICS LINK command.
  2. The EXEC interface stub DFHXCSTB calls the EXCI EXEC interface program which issues the following calls:
    • INITIALIZE_USER
    • ALLOCATE_PIPE
    • OPEN_PIPE
    • DPL
    • CLOSE_PIPE
    • DEALLOCATE_PIPE