ILE RPG Programmer's Guide
You cannot define return values for a main procedure, nor can you
specify that its parameters be passed by value.
The following considerations apply only to a cycle-main procedure:
- Because the cycle-main procedure is the only
procedure with a complete set of specifications available (except
the P specification), it should be used to set up the environment
of all procedures in the module.
- A cycle-main procedure is always exported,
which means that other procedures in the program can call the main
procedure by using bound calls.
- The call interface of a cycle-main procedure
can be defined in one of two ways:
- Using a procedure interface and an optional prototype
- Using an *ENTRY PLIST without a prototype
- The functionality of an *ENTRY PLIST is similar
to a prototyped call interface. However, a prototyped call interface
is much more robust since it provides parameter checking at compile
time. If you prototype the main procedure, then you specify how
it is to be called by specifying either the EXTPROC or EXTPGM keyword
on the prototype definition. If EXTPGM is specified, then an external
program call is used; if EXTPROC is specified or if neither keyword
is specified, it will be called by using a procedure call.
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