Why is Stack Memory Size Typically Limited to Around 1 MB, Despite the Theoretical Availability of RAM for Heap Memory?

Limitations of Stack Memory Size

Question:

Although heap memory can theoretically be allocated up to available RAM, why is the stack memory size so limited, typically around 1 MB?

Answer:

Unlike the heap, which can be allocated randomly, the stack must be stored in contiguous memory locations. This means that a large portion of virtual address space must be reserved for the stack, even if it is not immediately utilized.

For instance, in a 32-bit application with a 2GB virtual address space, a 2MB stack size limits the maximum number of threads to 1024. Increasing the stack size to 100MB would further reduce the thread limit to approximately 20. This can be problematic for applications like web servers and GUI programs.

Interestingly, this limitation also persists on 64-bit platforms. While the technical reasons are unclear, it is speculated that developers have become accustomed to stack best practices, such as avoiding huge object allocations on the stack and manually adjusting stack size when necessary. Therefore, the necessity for "huge" stack support on 64-bit systems remains unexplored.

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