When reading a PDSE directory that uses fixed-length blocked records, you can specify a BLKSIZE value of 256 or greater (the system ignores the LRECL value). You can calculate the block size and specify it in the BLKSIZE parameter of the DCB, or you can let the system determine the block size for you. Although the block size makes no difference in space usage for PDSEs, block size affects the buffer size of a job using the PDSE.

Related reading: See Block Size (BLKSIZE) for information about using BLKSIZE. Also see Reading a PDSE Directory.