IEA856W ATTEMPTED ACR OF LAST CPU - SYSTEM TERMINATED

Explanation
Alternate CPU recovery (ACR) attempted to remove
the last standard CP. There must be at least one standard CP online
in order for the system to run.

System action
The system issues wait state code 05A and enters
a non-restartable wait state.

Operator response
Contact the system programmer.

System programmer response
The problem might be due to a hardware
or software problem on the last standard CP.  If it is a hardware
problem, you will need to reconfigure the partition, so that it contains
at least 1 standard CP.  If it is a software problem, you probably
want to take a stand alone dump and then reIPL the system.

Source
Alternate CPU recovery (ACR)

Module
IEAVTACR