alloca with great difficulty
For starters, we might look at this fine patch removing alloca from a function in glibc. I’m mostly interested in the first chunk. That’s quite the incantation to prototype a function.
Another variant of the alloca spellbook is in bash. This version supports a different set of operating systems.
As Ben Franklin never said, “Beer is proof God loves us and wants us to be happy.” The ifdef maze one encounters trying to call alloca is proof your compiler hates you and you will be unhappy.