Non Heap Memory Usage

[Gaurav Hariani]

I see that irrespective of the number of clients connected to a broker 
or the number of messages being sent (or the size of messages)
the JMX Console reports that the broker is using 20Mb of Non-Heap Memory 
... is this a limit by design ... can I increase this limit to improve 
throughput?

Changing the UsageManager setting in the activemq.xml didn't seem to 
have any effect.

Gaurav