You can configure the maximum size of Java's memory allocation pool by passing the -Xmx flag to the Java process, e.g. -Xmx2048m. If you are running a Java-based service like Tomcat, this is often configured in the init script as part of the JAVA_OPTS environmental variable. Though different services will do this in different ways. Without knowing more about what you are running, it's hard to give a more specific answer.