The top memory consuming function is DomainBoundILStubClass.IL_STUB_PInvoke(UInt32). The module's base address is 0x00000000 so that's probably why it's the "UNKNOWN_MODULE" module. Here are the function details:
Function details
Function DomainBoundILStubClass.IL_STUB_PInvoke(UInt32)
Source Line
Allocation type C/C++ runtime allocation(s)
Allocation Count 525709 allocation(s)
Allocation Size 51.63 MBytes
Leak Probability 35%
There are zero stacks with this function at the top of the stack trace or near the top so I don't know what's calling it.
I'm assuming this is aggregating all the pinvoke'd calls to malloc. Is that correct? And since the "Allocation type" is C/C++, would that also include pinvoke'd calls to operator new?