A29

Explanation
The system was stopping itself when a program or
machine check occurred. While trying to recover from this program
or machine check, another program or machine check occurred. This
problem is probably a software error.

System action
The system enters wait state X'A29'.
Processing continues on other processors in the sysplex.

System programmer response
If the problem reporting databases
do not show a fix for the problem, contact the IBM® Support Center.

Source
Loadwait/Restart