Native threads and GC?

Hello.

We have a (32-bit, fwiw) C program that we are attempting to augment with a
CS function. The program runs in ~17 native threads, but our function only
runs in one of those threads. We call

     CHICKEN_initialize(0, 0, 0, C_toplevel);
     CHICKEN_run(C_toplevel);

after the thread is created, but then it goes off into libchicken and segfaults.
The last usefully-named function it calls is allocate_vector_2().

Is there a useful way to debug what's going on? The threads exchange messages, though
I don't believe any of them should be in the purview of CS's GC. Am I missing something
obvious?

Thanks!

-- 
Durward McDonell
[email protected]
240-228-2690 (DC)
443-778-2690 (Balt.)