stack & heap problem

i am trying to run some recursive factorial program on the nios2 evaluation kit.

The program was cross compiled in the suse linux and was dump into the board, as the value was exceeding 2000 the system is hanging and if the value exceeds 6000 the system is restarting.

And for a normal factorial program the system is restarting for 10k integer values(integer value in nios2 is 4bytes).

And if the heap i allocated exceeds morethan 1mb it errors as not enough memory.

can any one plzz say me what is the problem

kindly suggest.

thanks & regards

srikanth