Do not specify
DCB parameters RECFM, LRECL, or BLKSIZE; the external writer will allocate
them with record format VB and a system-optimal blocksize and logical record
length. For trace data sets on disk, we recommend a minimum of 10 cylinders
(3390). Secondary extents are ignored unless the NOWRAP option is specified
when the external writer is started. For example:
// EXEC PGM=IEFBR14
//TRACE DD DSN=SYS1.MVSS14.WAS390.CTRACE,UNIT=3390,VOL=SER=HPK19A,
// SPACE=(CYL,(20,0)),DISP=(NEW,CATLG),DCB=DSORG=PS