Re: Quick ILE question about service programs

[Jon.Paris@xxxxxx]

Definitive answer (It should be anyway since I've been teaching this stuff
since before it was released!! <g>)

A CALL (or CALLP where the prototype says EXTPGM) will _always_ be a
dynamic call.  Fully resolved at run-time.  No static binding of any kind -
no module copying - just the same old call we had back on S/38 and AS/400
before ILE.

An Eval or CALLB  (or CALLP when EXTPROC is specified) will either bind by
reference (to a Service Program) or bind by copy (to a procedure in a
separate Module object) - all this provided the call is not to a subproc in
the same module in which case the question is irrelevant.

Which of the two methods (copy or reference) is up to the programmer.

Copy will be used if the module containing the procedure is specified to
the CRTxxxMOD, CRTPGM or CRTSRVPGM command.  It will also be used if the
procedure is located by virtue of the module being listed in a binding
directory.  When copy is used a "copy" of the _module_ is included in the
*PGM object.  No run-time resolution is required.

Reference will be used if the service program containing the procedure was
listed to the CRTxxxMOD, CRTPGM, or CRTSRVPGM. As for bind by copy, it will
also be used if the service program is located by virtue of being listed in
a binding directory.  When reference is used no copy is made - rather a
"memo" is made that a specific service program and specific entry point
within that service program will be used.  Final linkage is made at
run-time.

Since all IBM routines (to the best of my knowledge) are always supplied in
service programs they will always be bound by reference which means that
they are not copied anywhere but linked at run-time.

Hope this helps.



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