Is your feature request related to a problem or challenge?

I think we can add a method to return the setting memory usage limit of pool.

It may be useful in some cases, for example when I want to know if the spilling will never to be triggered.

And it is actually natural to support this, just similar as the Vec::capacity

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

No response