COBOL Manual for TNS/E Programs (H06.03+)
Calling Other Programs and Routines
HP COBOL Manual for TNS/E Programs—520347-003
23-8
Operating System Routines
Special Register RETURN-CODE
The special register RETURN-CODE is accessible to an HP COBOL program that was
compiled with the PORT directive and uses the X/Open CALL statement to call a
function.The value of the function is returned in the special register RETURN-CODE,
whose description is:
01 RETURN-CODE EXTERNAL PICTURE S9(5) COMPUTATIONAL.
If the value of the function is greater than 99,999, arithmetic overflow occurs.
If the calling program cannot access RETURN-CODE, the value of RETURN-CODE is
unchanged.
Operating System Routines
Operating system routines are written in pTAL, HP C, and HP C++. The language in
which an operating system routine is written does not matter to the HP COBOL
program that calls it. Operating system routines execute in system code space, using
both system data space (for system tables) and user data space (for temporary
storage). When an HP COBOL program calls an operating system routine, it uses the
ENTER statement.
Some operating system routines never need to be called by HP COBOL programs—
file system routines, for example. File system routines are called by the HP COBOL
run-time routines to do their input and output operations. Although it is possible to call
file system routines explicitly from an HP COBOL program, you are advised not to
apply both HP COBOL I-O statements and explicit calls to file system routines to the
same file, as the HP COBOL run-time routines do significant preprocessing and
postprocessing.
Examples of operating system routines that are useful to an HP COBOL program are
ABEND, which signals an abnormal termination, and PURGEDATA, which erases all
data in a file but does not purge the file itself.
Topics:
•
Parameters
•
Resolution
•
Extensible and Variable Parameter Lists
•
Generations of Operating System Routines
Note. If you use operating system routines to do nowait I-O (you call a routine to do an input
or output operation and then call AWAITIO to wait for the operation to finish), be aware that the
HP COBOL run-time routines perform nowait I-O in some cases. The AWAITIO routine can
wait for any I-O operation to complete, or wait for the I-O operation on a specific file to
complete. It is best to apply AWAITIO to a specific file. Using the command PARAM WAITED-
IO ON allows you some latitude, however.