0B4

Explanation
The master subsystem could not make use of the
SYS1.PROCLIB data set defined by the IEFPDSI statement in the MSTRJCL.
This occurred for one of the following reasons: The master subsystem was unable to OPEN the PROCLIB data set.
The blocksize of the opened SYS1.PROCLIB data set was not a multiple
of 80.

System action
The system cannot function without an open SYS1.PROCLIB
data control block (DCB).  The system does not start the requested
subsystem.

System programmer response
Check for a valid data set name on
the IEFPDSI card in the MSTRJCL data set. Check for a valid blocksize
either on the IEFPDSI card or in the data set's format data set control
block (DSCB) in the VTOC. If the problem persists, search problem
reporting data bases for a fix for the problem. If no fix exists,
contact the IBM® Support Center.

Source
Initiator/terminator