Heap Memory is divided in to various categories. We can increase the size of eden and others to increase the memory size. Objects in Young generation are candidates for GC. If objects survive they will be promoted to Tenured space . Here objects do not undergo frequent GC.
-XX:-UseConcMarkSweepGC: Use the CMS collector for the old gen.
-XX:-UseParallelGC: Use Parallel GC for New Gen
-XX:-UseParallelOldGC: Use Parallel GC for Old and New Gen.
-XX:-HeapDumpOnOutOfMemoryError: Create a thread dump when the application runs out of memory. Very useful for diagnostics.
-XX:-PrintGCDetails: Log out details of Garbage Collection.
-Xms512m: Sets the initial heap size to 512m
-Xmx1024m: Sets the maximum heap size to 1024m
-XX:NewSize and -XX:MaxNewSize: Specifically set the default and max size of the New Generation
– XX:NewRatio=3: Set the size of the Young Generation as a ratio of the size of the Old Generation.
-XX:SurvivorRatio=10: Set the size of Eden space relative to the size of a survivor space.
Suman's Technology Notes 