BASIC RAM can use extra one kilobyte (or more!) by moving screen memory to $CC00 (52224).
Instructions:
LOAD "EXTRA1K.PRG",8,1
SYS 52131
Also see EXTRA1228.PRG for borrowing another 204 bytes from the cassette buffer and more.
See use of Jim Butterfield's SCREENMAP 64 and discussions of optimal memory layouts: https://techwithdave.davevw.com/2024/05/c64-ram-locations-for-programmable.html