Determining equivalent JCL

When you submit JCL that specifies symbols, the system responds as if you had coded the equivalent JCL (without symbols) produced by the following sequence of operations:

Determine the substitution texts. The system:
- Does not consider apostrophes that enclose symbols as part of their substitution texts.
- Considers parentheses that enclose symbols as part of their substitution texts.
- Compresses two-to-one the double apostrophes within symbols.
- Compresses two-to-one the double ampersands in symbols that are not enclosed in apostrophes.
- Does not compress double ampersands within symbols that are enclosed in apostrophes.
Substitute all symbols.
- Resolution of all symbols might determine the processing of subsequent statements. For example, a JCLLIB or INCLUDE statement might contain symbols that determine which statements are used in the job.
- Symbols on JCL records are treated as if they were resolved simultaneously.

The following example shows a procedure that defines JCL symbols:

   //EXAMPLE   PROC SYM1='What''''s up, Doc?',SYM2=(DEF),SYM3=&&&&TEMP1,
   //       SYM4='&&TEMP2',SYM5=&&TEMP3,TEMP3=TEMPNAME,
   //       SYM6=&TEMP3
   //S1        EXEC PGM=WTO,PARM='&SYM1',ACCT=&SYM2
   //DD1       DD   DSN=&SYM3,UNIT=SYSDA,SPACE=(TRK,(1,1))
   //DD2       DD   DSN=&SYM4,UNIT=SYSDA,SPACE=(TRK,(1,1))
   //DD3       DD   DSN=&SYM5,UNIT=SYSDA,SPACE=(TRK,(1,1))
   //DD4       DD   DSN=&SYM6,UNIT=SYSDA,SPACE=(TRK,(1,1))
   //          PEND

The PROC statement assigns the following substitution texts to the JCL symbols:

     SYM1      What''s up, Doc?
     SYM2      (DEF)
     SYM3      &&TEMP1
     SYM4      &&TEMP2
     SYM5      &TEMP3
     TEMP3     TEMPNAME
     SYM6      &TEMP3

The equivalent JCL produced by the substitution, when the procedure is expanded, is:

   //S1        EXEC PGM=WTO,PARM='What''s up, Doc?',ACCT=(DEF)
   //DD1       DD   DSN=&&TEMP1,UNIT=SYSDA,SPACE=(TRK,(1,1))
   //DD2       DD   DSN=&&TEMP2,UNIT=SYSDA,SPACE=(TRK,(1,1))
   //DD3       DD   DSN=&TEMP3,UNIT=SYSDA,SPACE=(TRK,(1,1))
   //DD4       DD   DSN=&TEMP3,UNIT=SYSDA,SPACE=(TRK,(1,1))

Note the following in the example:

SYM1 requires four apostrophes in its original definition because it is substituted into a parameter enclosed in apostrophes. The system compresses the apostrophes in the symbol definition when the value of the symbol is determined, and again when the EXEC PARM parameter is processed. The parameter passed to the WTO program is:
```
What's up, Doc?
```
The single ampersand produced by SYM5 in the DSN parameter of DD3 cannot be interpreted as the start of a new JCL symbol, since substitution is performed only once for a given statement. All symbols are treated as if they were resolved simultaneously. If the symbol TEMP3 defined on the PROC statement is not used elsewhere in the procedure, a JCL error results.
The symbol TEMP3 cannot be used to assign a value for the symbol SYM6 on the same statement. Because all symbolic parameters are resolved simultaneously, the value assigned to SYM6 cannot depend on another symbol defined at the same time. The system assigns the value &TEMP3, not &&TEMP2, to SYM6. Again, if the symbol TEMP3 is not used elsewhere in the procedure, a JCL error will result.