PBP RAM allocation - how to find available or total used RAM?

[Art]

I didn’t know you could mem allocate in PBP at run time at all.
How do you do that?

0x20 - 0x80 is just an arbitrary range I pulled out of the air.
It should be the entire RAM area of the particular pic’s memory map of one bank.
Then the same area is usually mirrored in other banks, so I’d just change the bank and run the same code again.