The stack of lisp objects used to pass and store arguments in the bytecode
VM and interpreter. The top of the stack is index 0 and all indexing
functions operate from top to bottom. The stack is partitioned into frames.
Each frame represents a function call and it’s arguments. The API is
designed so that code cannot access elements outside of their frame (doing
so results in a panic). Frames are added and removed with
push_frame and
pop_frame respectively.