In software, a stack overflow occurs when too much memory is use on the call stack. In many programming languages the call stack contains a limited amount of memory, usually determined at the start of the program. The size of the call stack depends on many factors, including the programming language, machine architecture, multi-threading, and amount of available memory. When too much memory is used on the call stack the stack is said to overflow; typically resulting in a program crash. This class of software bug is usually caused by one of two types of programming errors.