gistfile1.el

(require 'split-root)

(defvar anything-compilation-window-height-percent 50.0)
(defun anything-compilation-window-root (buf)
  (setq anything-compilation-window
        (split-root-window (truncate (* (window-height)
                                        (/ anything-compilation-window-height-percent
                                           100.0)))))
  (set-window-buffer anything-compilation-window buf))

(setq anything-display-function 'anything-compilation-window-root)