It may be necessary to set a few environment variables to configure the JVM used by JMeter. Those variables can be either set directly in the shell starting the jmeter script. For example setting the variable JVM_ARGS will override most pre-defined settings, for exampleJVM_ARGS="-Xms1024m -Xmx1024m" jmeter -t test.jmx [etc.]will override the HEAP settings in the script.