If you're on *NIX have you tried just invoking gstack or similar as an external process? https://linux.die.net/man/1/gstack

Or, indeed, getting a core dump and applying GDB to it. GDB seems generally pretty good at reconstructing stacks at arbitrary points in application runtime.

We've also used a combination of libunwind and https://linux.die.net/man/1/addr2line to produce good crash dumps when GDB is not necessarily available.