How much physical RAM do you have on the machine? Tomcat can allocate up to 25% of the physical RAM on the machine to itself, and free it up as the OS needs it. There was also a bug at 10.2.2 where the Tomcat process would use a lot of CPU if the memory ran up against that 25% threshold. That issue has been resolved in a patch:
ArcGIS for Server Security 2016 Update 2 Patch
BUG-000082423 - Under consistent load, the javaw.exe process at ArcGIS 10.2.2 for Server consumes 25% of the server's RAM, and any further request forces the process to use 100% of the machine's CPU.
It doesn't seem like you're seeing CPU issues, but it may be a patch you'll want to have installed if you don't already.
We have 32 gig of memory so, based on what you are saying, the javaw.exe process may consume up to 8GB of memory as long as the system is not under memory pressure. Thanks for that information (plus the pointer to the Update)