The SYSIN data set is an input data set that contains the utility command. The utility always requires the SYSIN data set.
The UTILINIT phase reads, parses, and verifies the utility command that is provided in this data set. The data set’s attributes must be specified as fixed length (RECFM is F, FB, or FBS), and the record length must be 80 columns (LRECL=80). The utility uses only columns 1 through 72.