Why this POSTTREE submission is giving SIGABRT ?

In the solution to POSTTREE I had tried using a stack and passed it in recursive function .
It is giving me SIGABRT error , although i doubt this is because of excessive memory allocation due to call by value mechanism .
But It would be great if someone could give some more insights to it .

Here is the Link To Solution .

Thanks in advance .

Are you sure there are no cases when recursion goes infinite ? Because in those cases program gives SIGABRT due to excess allocation of memory.

no i don’t think there is infinite recursion.

Thanks for the check.