enlarge-window

enlarge-window is an interactive compiled Lisp function in `window.el'.

It is bound to C-x ^.

(enlarge-window DELTA &optional HORIZONTAL)

Make the selected window DELTA lines taller.
Interactively, if no argument is given, make the selected window
one line taller. If optional argument HORIZONTAL is non-nil,
make selected window wider by DELTA columns. If DELTA is
negative, shrink selected window by -DELTA lines or columns.