Can't say for sure if it's the reason in this particular situation, but that would require dynamic memory allocation, and while it may seem backwards to reserve

Can't say for sure if it's the reason in this particular situation, but that would require dynamic memory allocation, and while it may seem backwards to reserve more memory than potentially needed on old memory-constrained systems, it is a pattern you see very frequently because on those systems, you actually know exactly how much memory you have. As a result, you know exactly how much memory you can "waste". Especially on single-tasking systems, it doesn't matter how much memory you waste, because no other program is affected by it. Or in other words: If you know you are guaranteed to have x KB of memory available and no other program can steal it, and you know that you don't need more than y KB, then why allocate up to y KB dynamically when you can just straight-up allocate y KB statically, which is less work?