A critical internal problem forced the ESP dSeries Server to shut down.
Tracelog showed that there was an influx in the java heap memory usage.
The issue could be caused by different factors, one of them may be a situation when a job's email notification with attached spool file was trying to deliver a spool file too big.
Avoid using email notification where attached spool file might take a big size, or constrain the spool file size with the
Maximum email attachment size in MB
parameter in the DE Admin/Topology/'Server Shared Parameters'.