//DD1B  DD    DSNAME=EVER,DISP=(NEW,KEEP),UNIT=3380,
//            RECFM=FB,LRECL=326,BLKSIZE=23472,
//            SPACE=(23472,(200,40))

DD statement DD1B defines a new data set named EVER on a 3380. The DD keywords RECFM, LRECL, and BLKSIZE contain the information necessary to complete the data control block.

//DD2B  DD    DSNAME=NEVER,DISP=(NEW,KEEP),UNIT=3590,
//            RECFM=FB,LRECL=256,BLKSIZE=204K

DD statement DD2B defines a new data set named NEVER on a 3590. The DD keywords RECFM, LRECL, and BLKSIZE contain the information necessary to complete the data control block. The block size, which in this example is 204 x 1024 = 208,896 bytes, must be divisible by the logical record length, and each program that reads or writes this data set must be capable of handling block sizes this large.