SOAP_http ://sap.com/ xi/ XI/ SystemCall - How to change "MaxThreads" param

Hi all,

Looking at MessageSystem, System Status (http://host:port/MessagingSystem/monitor/systemStatus.jsp), I found that the MaxThreads parameter for the queue SOAP_http://sap.com/xi/XI/SystemCall is "5" (probably the default value). Actually this is the bottleneck of incoming xi soap calls. Where can I change this parameter?

thanks!

roberti