Using &STR when supplying input using SYSIN JCL statements

When you submit a background job that invokes a program, you sometimes include a ‘//SYSIN DD *’ JCL statement that supplies the input statements. If any input statement contains leading blanks or is the same as a CLIST statement, enclose that statement in a &STR built-in function. For example, suppose a hypothetical language called SES has an IF-THEN-ELSE sequence. If you were to include such a sequence in the SYSIN input statements, you need to have to enclose it in an &STR built-in function as shown in the following background invocation of a hypothetical SES program called MATRIX.

PROC 1 FORMAT ACCT() CLASS(A)
CONTROL MAIN
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submit * end(nn)
//&SYSUID1 JOB   &ACCT,&SYSUID,CLASS=&CLASS;
//STEP1     EXEC  PGM=MATRIX
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//SYSIN     DD    *
&STR(  IF &FORMAT=1 THEN OPEN DS1)
&STR(ELSE OPEN DS2)
GETFILES 1-12
&STR(SET COLUMNS=GETFILES)
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nn

Only those input statements that contain leading blanks or are the same as CLIST statements are enclosed in &STR built-in functions. If the CLIST invoked MATRIX in the foreground, the &STR built-in functions need to be unnecessary because the program's statements need to appear in the data set containing MATRIX. Thus, they need to be associated with the program, not the CLIST.