What version of JBoss AS, JBoss EAP or WildFly are you using?
James R. Perkins
Sometimes the GC is not the real problem. I've seen often that there is a threshold for number of requests or DB response times, if you reach it the GC becomes crazy because the objects are keept too long in memory and you run out of mem-space which end in a frequent full-GC.
In such situation a bit more memory will help to survive this peak.
In any case I would recommend to monitor as much as possible around that, it often will give you a better understanding why you run into this issue
We are using JBoss EAP 6.0.1 GA.
We began to monitor application via java agent - hopefully we see which classes were not able to be Full GCed and resist in old generation.
As you use EAP you might have access to the knowledgebase, there you might find some helpful articles.
Often it is related to a threshold and after that point the old gen get swamped. If there is no memory leak you may have to adjust the heap sizes and GC strategy.