The conventional MVS™ variable-length parameter string is the same parameter list as the one generated by ADDRESS LINKMVS with one parameter, and by JCL with EXEC PGM=,PARM=. Any program can easily use this parameter list form. Note that this is a single-item variable-length parameter list. The high bit is on in the parameter address word and length is a halfword that has a value less than 16384.

Figure 1. Example of parameter list

PL/I usage might include the following statements:

DCL PLIRETV BUILTIN;
  DCL BPXWDYN EXTERNAL ENTRY OPTIONS(ASM INTER RETCODE);
  DCL ALLOC_STR CHAR(100) VAR
        INIT('ALLOC FI(SYSIN) DA(MY.DATASET) SHR');
  FETCH BPXWDYN;
  CALL BPXWDYN(ALLOC_STR);