How many stacks are required in finite automata?

Excuse me, I'm curious about the intricacies of finite automata and their operation. Could you elaborate on the role of Stacks in their functioning? Specifically, how many stacks are typically required for a finite automaton to function effectively? Does the number of stacks vary depending on the complexity of the automaton or the task it's designed to accomplish? Clarifying this aspect would greatly assist me in understanding the fundamental principles behind finite automata and their implementation.