What is top max 1 in stack?

Could you please elaborate on what you mean by "top max 1 in stack"? It seems like you're referring to a specific concept in programming or computer science, but the terminology isn't entirely clear. Are you referring to a data structure such as a stack, and specifically to the operation of retrieving or modifying the top element of the stack with a maximum value of 1, or perhaps a specific limit on the size of the stack? It would be helpful if you could provide more context or clarify your question.