Stack

A stack is a memory area used to store and retrieve information in LIFO (last in, first out) order. It is very commonly used in basically any computer system and any program.

Basic operations

There are basically only 2 operation which can be performed on a stack:

• Push - Adding information to the stack
• Pop - Retrieving information from stack

A stack needs a stack pointer (SP), which typically points to the next address to either push or pop from. Stacks typically grow downward, so pushing a 32-bit value onto a stack will decrement the stack pointer by 4, where pop a 32-bit value does the opposite and increments the stack pointer by 4.

Stack overflow

One problem that is hard to control and avoid is stack overflow. It happens when the application has pushed more data onto the stack that actually fit, thereby overwriting other data areas or writing into areas that are not data. In any case, the effects will usually create problem when program execution continues, very likely a crash of the program. This is a problem especially in smaller Embedded Systems, which do not have an MMU or MPU to control the access to the stack.