If your system has gone down with a power failure, it’s probably stopped immediately and not been able to write out any joblogs.
I guess it didn’t switch over to battery backup before it went down? If the system isn’t running, it can’t write logs.
The term “joblog” has two general meanings. One is the job’s external message queue and any active program message queues while the job is running; this is what gets copied to your screen when you take option 10 from the DSPJOB menu. The other meaning is the spooled report of the content of those message queues that is created when a job ends.
<i>Why did I not get a full joblog?</i>
Because you lost a power supply and the system crashed. There wasn’t time to copy the job’s message queue to the spooled representation of a “joblog”.