What If...?

What if you were trapped in the caverns of the Grand Canyon with an arm caught beneath a boulder, could/would you cut off your limb to survive? Would you just wait and die there and not even try? Its a very hard thing to imagine, and a young man did it in the recent past. Im watching the movie 127 Hours which is the Hollywood take on this event. So, again I ask, would you sacrifice your limb to survive?