Stakkminne

Stakkminne, or stack memory, is a region of a process's address space that stores temporary data created during function calls. It is organized as a last-in, first-out (LIFO) structure called the call stack. The stack contains return addresses, function arguments, and local variables, stored in what are called stack frames. When a function is called, a new frame is allocated on the top of the stack; when the function returns, the frame is removed.

Access to stack memory is typically fast due to spatial locality and caching. Allocation and deallocation are automatic and determined by the program's call flow; there is no explicit free operation. The stack usually grows downwards toward lower memory addresses on common architectures, though some use an upwards-growing implementation; the direction is architecture-dependent.

Stack capacity is finite, and unbounded recursion or large local arrays can overflow the stack, causing a stack overflow or crash. Operating systems implement protections such as guard pages and canaries to detect or mitigate overflow and control flow abuses. Stack memory is also subject to security concerns like return-oriented programming; mitigations include stack canaries, NX/DEP, and ASLR in broader contexts.

Compared with heap memory, stakkminne has a limited lifetime tied to function scope and program flow, and is freed automatically when a function returns. Heap memory is for dynamically allocated objects with manual or automatic lifetime management.

Understanding stakkminne helps explain function calls, recursion, and performance characteristics in many programming languages.