I used to work on a (now defunct) RTOS whose C runtime didn't support alloca. Functions were all compiled down to a portable bytecode representation that had to

I used to work on a (now defunct) RTOS whose C runtime didn't support alloca. Functions were all compiled down to a portable bytecode representation that had to statically declare the stack usage, so there was no way to have a function with variable stack size. Not having a real alloca was occasionally an issue for porting C code to it (but less annoying than not having fork()).