Instruments, ObjectAlloc not showing stack?

[Daniel Hazelbaker]

I have a memory "leak" (not really a leak, but I can't figure out  
where the memory is being allocated) that I am trying to track down.   
When running my application under Instruments (for those of you on the  
quartz-dev list this is the problem with the new Mac Pro + CV) I see a  
good solid usage of memory.  Then randomly it spikes up and never  
releases.  And I mean spikes, as in going from 180MB usage up to 300MB  
usage.  It then stays  solid there until the next spike when it jumps  
up another ~100MB.

When I look at "normal" allocations I see the call stack for how the  
memory block got allocated.  When I look at the allocations of these  
large blocks (and they are large, usually around 8MB each) it shows  
that calloc did the actual allocation and simply shows  
"libSystem.dylib" as next up in the stack and nothing else.  Is there  
a way to track down how this memory is actually being allocated?

I am rather stumped since leaks show it is not leaking memory yet  
something, apparently in the system, is allocating memory in huge  
chunks randomly.

Daniel