SRF in C

in section _37.7.1.2. RETURN NEXT_ of the docs, it says that "PL/pgSQL
stores the entire result set before returning from the function".

Is the same true for C, and if so, should we document it in
_33.7.9. Returning Sets from C-Language Functions_ ?

It could be important if someone wanted to return a huge amount of data
from an SRF and it was larger than available RAM.

Regards,
    Jeff Davis