Taking the dump should not have any performance impact on the system. A manual dump can be taken at any time (with no additional configuration required) from the command line or the ESMAC interface. However, a region should be configured to generate a system dump whenever a System Abend occurs. This is usually configured in the Enterprise Server Admin Console (i.e. ‘Dump on System Abend’).
Additionally, “Dump on Transaction Abend” can be set in ESMAC so that any abending transactions will also cause a dump to be generated.
Dump information will be written to the current casdump file (casdumpa.rec, casdumpb.rec or casdumpx.rec), and includes the current contents of process memory, server control blocks and the local and system trace tables.
We recommend you take a dump for most problems when they occur, and whilst the system is in the failed state.