Your application program may require the coding of the DCB parameter on the DD statement. And, it might operate differently if the DCB parameter is coded.
If you specify an external writer on the SYSOUT parameter, the external writer may require the DCB parameter on the DD statement that was used to create the data set.
Consult the documentation for your application program or the external writer, if appropriate, for further information about DCB subparameters that may be required or recommended.
//OUT3 DD SYSOUT=(H,WRTPGM),DCB=(RECFM=FB,LRECL=133,BLKSIZE=532)