An in-stream procedure must begin with a PROC statement, end with a PEND statement, and include only the following other JCL statements: CNTL, comment, DD, ENDCNTL, EXEC, IF/THEN/ELSE/ENDIF, INCLUDE, OUTPUT JCL, and SET. You must observe the following restrictions regarding in-stream procedures:

• Do not place any JCL statements (other than the ones listed here) or any JES2 or JES3 control statements in the procedure.
• Do not define one in-stream procedure within another, that is, do not use nested in-stream procedures. Refer to Nested procedures for information on methods for nesting procedures.
• Do not use an in-stream procedure if the procedure will be run as a started job under the MASTER subsystem, that is, includes a JOB statement and is started via a START command such as S membername,SUB=MSTR.