The stack and StackOverflowError

Definition

Every thread has its own stack that holds method calls and local variables. If calls nest too deeply, usually from a recursion that never stops, the stack runs out and Java throws StackOverflowError. The stack size is set with -Xss.

Example code

A runaway recursion is caught

class Demo {
    static int depth = 0;

    static void recurse() {
        depth++;
        recurse();                         // no stop condition: each call adds a frame to the stack
    }

    public static void main(String[] args) {
        try {
            recurse();
        } catch (StackOverflowError e) {
            System.out.println("stack ran out of space, reached a depth above 1000: " + (depth > 1000));
        }
        // a bigger stack for deep but valid recursion: java -Xss2m ...
    }
}

// Output:
// stack ran out of space, reached a depth above 1000: true