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When you are programming in a language that allows you to use automatic allocation for very large objects, when and how do you worry about stack size? Are there any rules of thumb for reasoning about stack size?
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Stack overflow The stack has a limited size, and consequently can only hold a limited amount of information. On Windows, the default stack size is 1MB. On some unix machines, it can be as large as 8MB. If the program tries to put too much information on the stack, stack overflow will result.
Stacks are temporary memory address spaces used to hold arguments and automatic variables during invocation of a subprogram or function reference. In general, the default main stack size is 8 megabytes.
FWIW, stack size is not fixed, it expands at runtime as necessary, but stack limit is fixed. If your program only uses 40 bytes of stack (plus a little more for the run-time system) and the OS by default allocates an 8MB stack for the process (like Linux does), you still have almost 8MB stack left over.
Because all threads in a process share the same address space, they have to divide it between them. And after the operating system has taken its part, there is "only" 2-3 GB left for an application. And that size is the limit for both the physical and the virtual memory, because there just aren't any more addresses.
When you are programming in a language that allows you to use automatic allocation for very large objects ...
If I want to allocate a very large object, then instead of on the stack I might allocate it on the heap but wrapped in an auto_ptr (in which case it will be deallocated when it goes out of scope, just like a stack-resident object, but without worrying about stack size).
... when and how do you worry about stack size?
I use the stack conservatively out of habit (e.g. any object bigger than about 512 bytes is allocated on the heap instead), and I know how big the stack is (e.g. about a megabyte by default), and therefore know that I don't need to worry about it.
Are there any rules of thumb for reasoning about stack size?
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You care about it on a microcontroller, where you often have to specify stack space explicitly (or you get whatever's left over after RAM gets used for static allocation + any RAM program space).
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