Editing Job Control Language (section)

===Parameterized procedures===
OS JCL procedures were parameterized from the start, making them rather like [[Macro assembler|macros]] or even simple [[subroutine]]s and thus increasing their [[Code reuse|reusability]] in a wide range of situations.<ref>Ashley and Fernandez, ''Job Control Language'', pp. 129–131.</ref>
<syntaxhighlight lang="jcl">
//MYPROC PROC FNAME=MYFILE01,SPTYPE=TRK,SPINIT=50,SPEXT=10,LR=100,BLK=1000
.....
//NEWFILE DD DSN=&FNAME,UNIT=DISK,SPACE=(&SPTYPE,&SPINIT,&SPEXT),
//           DCB=(LRECL=&LR,BLKSIZE=&BLK),DISP=(NEW,CATLG,DELETE)
....
</syntaxhighlight>
In this example, all the values beginning with ampersands "<code>&</code>" are parameters which will be specified when a job requests that the procedure be used. The PROC statement, in addition to giving the procedure a name, allows the programmer to specify default values for each parameter. So one could use the one procedure in this example to create new files of many different sizes and layouts. For example:
<syntaxhighlight lang="jcl">
//JOB01  JOB ..........
//STEP01 EXEC MYPROC FNAME=JOESFILE,SPTYPE=CYL,SPINIT=10,SPEXT=2,LR=100,BLK=2000
or
//JOB02  JOB ..........
//STEP01 EXEC MYPROC FNAME=SUESFILE,SPTYPE=TRK,SPINIT=500,SPEXT=100,LR=100,BLK=5000
</syntaxhighlight>