How to Increase Heap Size of Jvm

Increase heap size in Java

You can increase to 2GB on a 32 bit system. If you're on a 64 bit system you can go higher. No need to worry if you've chosen incorrectly, if you ask for 5g on a 32 bit system java will complain about an invalid value and quit.

As others have posted, use the cmd-line flags - e.g.

java -Xmx6g myprogram

You can get a full list (or a nearly full list, anyway) by typing java -X.

How to increase application heap size in Eclipse?

In the run configuration you want to customize (just click on it) open the tab Arguments and add -Xmx2048min the VM arguments section.
You might want to set the -Xms as well (small heap size).

Increase default max heap space in Eclipse

You can set default arguments for a JVM used to run Java apps in the Preferences. Go to the 'Java > Installed JREs' page. Select the JRE/JDK you are using and click the 'Edit...' button. In the edit dialog there is a 'Default VM arguments' field where you can put your settings.

Note: The eclipse.ini lines only change the settings for Eclipse itself, they aren't relevant to running Java apps from Eclipse.

how to increase heap space of JVM in netbeans

Run->Set Project Configuration->Customize...
You can enter your VM options in Run tab. Use the -Xmx[size] flag to increase the heap size.
As size you can use for example 512m for 512MB or 2g for 2000MB.

Increasing Heap Size on Linux Machines

Changing Tomcat config wont effect all JVM instances to get theses settings.
This is not how it works, the setting will be used only to launch JVMs used by Tomcat, not started in the shell.

Look here for permanently changing the heap size.