In response to this StackOverflow question, here’s a simple Jython wsadmin script which will display the JVM min and max heap sizes for the specified Application Server.

# Usage: wsadmin -f server  
server = AdminConfig.getid('/Server:'+sys.argv[0]+'/')  
jvm = AdminConfig.list('JavaVirtualMachine', server)  

print 'initialHeapSize: ' + AdminConfig.showAttribute(jvm, 'initialHeapSize')  
print 'maximumHeapSize: ' + AdminConfig.showAttribute(jvm, 'maximumHeapSize')

Update: the above only obtains the heap size if a custom value has been explicitly configured. From this other post, here’s a mechanism which will obtain the maximum heap size otherwise (note there doesn’t appear to be an attribute to obtain the minimum heap size):

jvmName = AdminControl.completeObjectName('WebSphere:type=JVM,process=MyServerName,*')  
print AdminControl.getAttribute(jvmName,'maxMemory')