Is there a way for process to ask about its own memory usage?

Something perhaps like the C functions that were available in the dark
ages on other computer systems that could tell how much memory had
been allocated but not freed so far? Or some reasonable surrogate?

Yes,I know there are administrative tools that let me survail all the
processes in the system. But isn't there something the program can do
for itself without that level of agony?

-- hendrik