access bash from C program?

[Labitt, Bruce]

I've been scratching my brains here a bit.  Is there an easy way to get
access to the shell (bash) from within a C program?  I left my K&R at
home...
My googling has not particularly enlightened me, either...

I'd like to run the equivalent of the command "$ ulimit -s hard"

I need to do this because I need much more stack than the terminal
window ordinarily allows.  (Can't run FFTs > 256K without above
command.)

TIA
-Bruce