DINRREFD requests the name of the JCL DD statement from which the attributes of the specified data set were copied. When you code DINRREFD, # must be 1, LEN must be at least 26 and can be longer, and the PARM field must be the length specified by the value in LEN.
If there is a JCL DD statement from which attributes were copied, the system returns the name of the DD statement into PARM. The name can be a ddname, a stepname.ddname, or a stepname.procstepname.ddname where ddname is the label on a JCL DD statement, and stepname and procstepname are labels that appear on JCL EXEC statements. If the name is fewer than 26 bytes long, it is left-justified and padded to the right with blanks. The system also returns 26 into LEN.
KEY # LEN PARM
C00D 0001 001A - - -...