在java中使用大内存大小的最佳实践是什么？

I have an application server server and 64 GB memory on it. And a java web application on it. What is a best practice to utilize all these 64 GB? I need store a large set of objects (HashSet) Is it a best solution to use -Xms -Xmx ? But will GC working well? Should I use 3rd party solutions like cache libraries (memcache and etc.) ?I have an application server server and 64 GB m