The main EXEC interface module, DFHEIP, which is called when an EXEC CICS®
command is executed in a user application program.
A parameter list is
passed, in which the first argument (referred to as arg-zero) contains a group
code and a function code as the first 2 bytes.
The group code in general indicates the CICS component associated with
the command being executed. In subsequent processing it is this code alone
which determines which EXEC processor module (see below) is called from DFHEIP.
The function code identifies the actual command being executed.
Note:
DFHEIP is link-edited with other modules to form
the application interface program (DFHAIP) load module. DFHEIPA (next to be
described) is one of these modules.
The DFHEIPA module, which handles the allocation and freeing of dynamic
storage (mapped by DFHEISTG) for assembler-language application programs in
response to DFHEIENT and DFHEIRET calls respectively.
A set of EXEC processor modules, each of which is called from DFHEIP,
and which performs the first level of analysis of the command being executed.
The processor then calls the appropriate CICS domain to complete the execution
of the command.
A set of EXEC stubs, one for each of the application languages: COBOL,
PL/I, C, and assembler language. The appropriate stub must be link-edited
at the front of each CICS application program, and provides the mechanism
for getting to the correct entry points in DFHEIP.
The DFHAPLI module, which is called at the initialization and termination
of each application program.