frame-windows-min-size

frame-windows-min-size is a compiled Lisp function in `window.el'.

(frame-windows-min-size &optional FRAME HORIZONTAL IGNORE PIXELWISE)

Return minimum number of lines of FRAME's windows.
HORIZONTAL non-nil means return number of columns of FRAME's
windows. The optional argument IGNORE has the same meaning as
for `window-resizable'. PIXELWISE non-nil means return sizes in
pixels.