Do you know by change where I can find which objects/threads are responsible for the increase in the GC Heap?
-Maybe just take some threadumps and then use MAT or ISA to analyze the dumps, you can also use the threadumps feature in workstation.
Configure Thread Dumps - CA Application Performance Management - 10.7 - CA Technologies Documentation
-try to deploy the below additional agent extension, it might be able to help you obtain the threads information you need.
Thank you Sergio.