Why does Ants pool prefer using loop queue when preallocating memory, instead of using stack data structure?

[EddieChan1993]

if p.options.PreAlloc {
	if size == -1 {
		return nil, ErrInvalidPreAllocSize
	}
	p.workers = newWorkerArray(queueTypeLoopQueue, size)
} else {
	p.workers = newWorkerArray(queueTypeStack, 0)
}