Can the StackOverflowException occur using a single method in C#?

Question

StackOverflowException occurs when a method is called recursively, infinitely many times. Different stack frames are allocated to each recursive call -- multiple stack frames are used in this case. As we know, a stack frame is allocated to each method call. Can the stack overflow when using a single method in C# (using a single stack frame)?

Answer 1

can the stack be overflown with using single method

Sure:

static unsafe void Main()
{
    for(int i = 0; i < 50; i++)
    {
        // fails on i=18 for me
        long* ptr = stackalloc long[10 * 1024];
    }
}

A stack overflow happens when the stack is fully consumed. There are multiple ways to do that; recursion is just one of them. stackalloc creates a pointer to (or more recently: a span over) a block of memory at the current stack-frame, extending the current stack-frame; it will be conceptually reclaimed (although in reality, this just means changing a single number) when you return (or throw, etc) from the method that allocated it.

---

Another way would be to create an absurdly over-sized value-type:

static class P
{
    static void Main() => Foo();
    static void Foo() => Bar(default);
    static void Bar(FatStruct2097152‬ a) => Console.WriteLine(a);
}

struct FatStruct64 {
    private long a, b, c, d, e, f, g, h;
}
struct FatStruct512 {
    private FatStruct64 a, b, c, d, e, f, g, h;
}
struct FatStruct4096 {
    private FatStruct512 a, b, c, d, e, f, g, h;
}
struct FatStruct32768 {
    private FatStruct4096 a, b, c, d, e, f, g, h;
}
struct FatStruct262144 {
    private FatStruct32768 a, b, c, d, e, f, g, h;
}
struct FatStruct2097152 {
    private FatStruct262144 a, b, c, d, e, f, g, h;
}