COBOL Manual for TNS/E Programs (H06.03+)

Calling Other Programs and Routines
HP COBOL Manual for TNS/E Programs—520347-003
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Operating System Routines
Resolution
The compiler leaves operating system routines unresolved, and the loader resolves
them during fixup (see Fixup). The compiler is able to leave references to operating
system routine calls unresolved because a file named ECOBEXT, which is part of
every HP COBOL RVU, contains dummy versions of all the operating system routines.
Another file, EXTDECS, contains pTAL external declarations for the environment
routines and is part of every operating environment RVU. A third file, ZSYSCOB,
contains HP COBOL source declarations of data items and structures for Guardian
procedures and operating environment messages.
There are two reasons to have your system manager change the files ECOBEXT and
EXTDECS:
•
You have additional routines that you want to be left unresolved until fixup (ask
your system manager to add dummy versions of them to the ECOBEXT or
EXTDECS file).
•
The formal parameter list of one or more system routines changes from extensible
to variable, in which case the EXTDECS file and the ECOBEXT file must also
change.
For more information on the ZSYSCOB file, see the Guardian Application Conversion
Guide.
Extensible and Variable Parameter Lists
An operating system routine can have an extensible or a variable parameter list. Both
extensible and variable parameter lists allow you to omit unnecessary actual
parameters in the ENTER statement. The difference between extensible and variable
parameter lists is in what happens when new formal parameters are added to the
routine, as sometimes happens to operating system routines with a new RVU of the
operating environment.
When new formal parameters are added to an operating system routine that has an
extensible parameter list, you do not have to recompile programs that call the routine.
If an operating system routine’s formal parameter list changes from variable to
extensible, the code that was compiled to expect a variable parameter list can usually
call the new version of the routine that has an extensible parameter list (at a slight
performance penalty). For more information about variable and extensible parameter
lists, see the pTAL Reference Manual.