Heap out of Memory Issue

Hi, I am using cfthread in my application and the cfthread uses one java library to download data from different servers. Generally we download 50-60MB data or 50,000 - 60,000 images in small batches by looping.

Most of the times I facing the issue out of memory for heap.

Below is my JVM settings.

java.args=-Duser.timezone=America/Chicago -server -Xmx2048m -Xms2048m -Dsun.io.useCanonCaches=false -XX:MaxPermSize=256m -XX:PermSize=256m -XX:+UseParallelGC -Dsun.rmi.dgc.client.gcInterval=600000 -Dcoldfusion.fckupload=true -Dsun.rmi.dgc.server.gcInterval=600000 -Xbatch -Dcoldfusion.rootDir={application.home}/ -Djava.security.policy={application.home}/servers/cfusion/cfusion-ear/cfusion-war/WEB-INF /cfusion/lib/coldfusion.policy -Djava.security.auth.policy={application.home}/servers/cfusion/cfusion-ear/cfusion-war/WE B-INF/cfusion/lib/neo_jaas.policy

Can any one please suggest where do I make any JVM related changes for optimize use of heap memory?

Or How can I able to detect whether any other issue(memory leak) is there in my application?