Segmentation fault, _malloc_prefork () - debugging help needed

[Unga]

Hi all

I'm developing an multi-threaded application on FreeBSD.

When it is running for sometime, it develops a Segmentation fault.

The ddd debugger shows following:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 296c6580 (LWP 100137)]
0x28ee390e in _malloc_prefork () from /lib/libc.so.7

How could I know the exact line in source where this issue develops?

Many thanks in advance.

Best regards
Unga