segmentation fault at to small stacksize( ulimit -s)

Hello,

i have a script which ends up in a segmentation fault.(i think memory leak)
if i increase stack size with ulimit -s the script shows correct error:
Fatal error: Allowed memory size of 41943040 exhausted (tried to allocate 16 
bytes)

the default of stack size is 8192 kb
why is there a seg.fault if stack size is on default value and not a correct 
error-message.
What is the recommended way to avoid this?

Thanks,
Hajo