IBM (mainframe) and dynamic / static CALLs

From: William M. Klein (wmklein_at_nospam.netcom.com)
Date: 06/15/04 

Date: Tue, 15 Jun 2004 19:27:54 GMT

Just because there may be some confusion - from another thread, the following is
true for IBM mainframes (slight variations exist for VSE and VM - so this is
*most* accurate for MVS, OS/390, and z/OS) *and* COBOL (other languages and
products may include additional variations)

1) The older (no longer available in current compilers) RES/NORES compiler
option determined whether internal calls to IBM supplied "run-time routines"
were resolved at link-edit or run-time. (Current compilers require that almost
all IBM supplied run-time support be accessed at run-time)

2) There are internal differences between the (more recent) BINDER and the
Linkage-Editor, but these *normally* have little or no impact on COBOL
programmers.

3) When the NODYNAM compiler option is specified,
   CALL "literal" statements are resolved at linkage/binding time
   CALL identifier statements are resolved at run-time

4) When the DYNAM compiler option is specified, all CALL statements are resolved
at run-time

5) The NCAL linkage editor statement can cause "normally" link-edit resolution
to be "skipped". Although this used to be used "medium-often" - its use (as far
as I know) has diminished in recent years. There may be other
Binder/Linkage-Editor control statements that can impact all of what I am saying
in this note.

6) IBM *clearly* documents that compiling with the NODYNAM compiler option
results in semantics that are NOT ANSI/ISO (any variation) conforming. This is
PRIMARILY due to the fact that CANCEL statements are ignored. OTOH, NODYNAM is
required for some IBM products such as CICS.

   ***

To the extent that these generalizations apply to other environments (IBM or
otherwise) depends entirely on the Operating System facilities, the compiler,
and the run-times. 

-- 
Bill Klein
 wmklein <at> ix.netcom.com

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