Example: using different input files
This example shows that you use the same COBOL program
to access different files by coding a DD
statement
or an export
command before the programs runs.
Consider a COBOL program that contains the following SELECT
clause:
SELECT MASTER ASSIGN TO DA-3330-S-MASTERA
Assume the three possible input files are MASTER1
, MASTER2
,
and MASTER3
. Before running the program, code one
of the following DD
statements in the job step that
calls for program execution, or issue one of the following export
commands
from the same shell from which you run the program:
//MASTERA DD DSNAME=MY.MASTER1,. . .
export MASTERA=DSN(MY.MASTER1),. . .
//MASTERA DD DSNAME=MY.MASTER2,. . .
export MASTERA=DSN(MY.MASTER2),. . .
//MASTERA DD DSNAME=MY.MASTER3,. . .
export MASTERA=DSN(MY.MASTER3),. . .
Any reference in the program to MASTER
will
therefore be a reference to the file that is currently assigned to
the ddname or environment-variable name MASTERA
.
Notice
that in this example, you cannot use the PATH(
path)
form
of the export
command to reference a line-sequential
file in the z/OS® UNIX file system, because you
cannot specify an organization field (S-
or AS-
)
with a line-sequential file.