You call it "automatic reload", but is a software crash. You need "show tech", particularly "show stacks" to see where in the code is crashing. And, customer level CCO access to decode this information.
If you don't want to do that, upgrade IOS and chances are it won't happen anymore.
Also check your processing engine. The NSE-1 has a known hardware bug (search TAC cases). We have several of these engines and with certain code levels they were hanging and sometimes rebooting all the time. We've replaced most of them at our expense.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...