Chapter 5 – The Stack

Core idea

The stack manages function calls and local variables.

Stack characteristics

• Grows from high to low memory
• Each function call gets a stack frame
• Stores:
  • Local variables
  • Return address
  • Saved registers

Important registers

• SP (Stack Pointer) – Top of the stack
• BP (Base / Frame Pointer) – Fixed reference for variables
• LR (Link Register) – Return address
• PC – Next instruction

Function calls

• Caller saves state
• Callee gets new stack frame
• On return:
  • Stack is popped
  • Execution resumes via return address

Exam traps

• Stack is limited
• Stack overflow = deep recursion or large locals
• Stack variables die when function returns