Explanation

An error occurred during LOGON processing. An SVC dump is requested if one of the following messages is issued:
IKJ56451
An installation-exit error occurred
IKJ56452
A system error occurred
IKJ600I
An I/O, OBTAIN, or OPEN error occurred
IKJ603I
An installation-exit abend occurred
IKJ608I
A TSO service routine error occurred

The areas dumped are NUC, RGN, SQA, and LPA if TSO dump is requested.