Page Cache getting full on server (Linux)

Hello,

We have Appian 17.4 running on RHEL 6.8 server with 32 GB RAM and 8 CPU. The app server is JBoss (eap 6.4) and JDK (1.8.0_121). As soon as the appian is up and running, the memory and cache is almost getting full (90%). Even if we add more memory, it's still going up to 90% and as users  (less than 10) start using it, memory is going down to 95% or more.

My questions are:

- Can we run Linux "page cache" script on the server every few hours? If not, why? Would this create any issue for the application?

- Are there are best practice or recommendations for memory tuning on Appian

- Are there any logs to see for memory leaks