IEA525W

Explanation
A user interaction module (UIM) asked to use the
device class extension of the unit control block (UCB) for a device.
 The system did not build a UCB for that device because of a logic
error in the UIM.
In the message text: modname
The unit information module (UIM).
s-
dev
The device number. The device number is prefixed by the subchannel
set identifier (s-) when appropriate.

System action
System initialization ends.  The system enters
nonrestartable wait state X'0B4'.

System programmer response
See the system programmer response
for wait state X'0B4'.

Source
Input/output supervisor (IOS)

Module
IOSIUCB