stacksize

Stacksize refers to the amount of memory allocated for a thread’s call stack in a computing system. The stack is the region used to store return addresses, function parameters, and local variables for active function calls. It is typically a fixed-size region reserved for each thread, and the data stored there grows as functions call other functions. In many architectures the stack grows downward in memory, and a stack overflow occurs when the available space is exhausted.

In multi-threaded environments, every thread has its own stack, and the total stack memory used by a program is the sum of all thread stacks. The designated size affects how deep function calls can be nested and how large local data can be on the stack. If the stack is too small relative to the call depth and local allocations, a stack overflow error or crash can occur. Conversely, a very large stack per thread increases the program’s overall memory footprint.

Configuration and limits vary by platform and language. Operating systems provide limits such as per-process or per-thread stack sizes (for example, using ulimit -s or setrlimit on Unix-like systems, and thread attributes on POSIX threads). Languages and runtimes may expose options to adjust stack size, such as Java’s -Xss flag. Some environments also allow dynamic growth with guard pages, while others use a fixed-size stack. Best practices include matching stacksize to expected recursion depth and local allocations, and preferring heap allocation for large data when possible to avoid stack overuse.