A SYMNAMES DD statement indicates you want DFSORT or ICETOOL to do symbol processing. It specifies the SYMNAMES data set (SYMNAMES for short), which can consist of one DFSORT symbol data set or many concatenated symbol data sets.

A symbol data set can be a sequential data set, a partitioned member or a DD * data set; all three types can be concatenated together for the SYMNAMES DD. Each symbol data set must contain SYMNAMES statements describing the symbols for fields and constants to be used for the DFSORT or ICETOOL application. Each symbol data set must have the following attributes: RECFM=F or RECFM=FB and LRECL=80.

For best performance, use a large block size, such as the system determined optimum block size, for all DFSORT symbol data sets.

If a SYMNAMES DD statement is not present, or SYMNAMES is empty, symbol processing is not performed.