Mock Service - GC overhead limit exceede

I am currently evaluating soapui to create mock service for ews. I import wsdl and other files and that worked fine. I could create a soap service with one of the operation.

Now whenever i create a new response for a given operation, i get error "gc overhead limit exceeded". Can you please help.

I have allowed soapui to use upto 4 gig through .vmoptions.