Function: minibuffer-depth-indicate-mode

Toggle Minibuffer Depth Indication mode.
With a prefix argument ARG, enable Minibuffer Depth Indication
mode if ARG is positive, and disable it otherwise. If called
from Lisp, enable the mode if ARG is omitted or nil.

Minibuffer Depth Indication mode is a global minor mode. When
enabled, any recursive use of the minibuffer will show the
recursion depth in the minibuffer prompt. This is only useful if
`enable-recursive-minibuffers' is non-nil. (fn &optional ARG)

Variable: minibuffer-depth-indicate-mode

Non-nil if Minibuffer-Depth-Indicate mode is enabled.
See the command `minibuffer-depth-indicate-mode' for a description of this minor mode.
Setting this variable directly does not take effect;
either customize it (see the info node `Easy Customization')
or call the function `minibuffer-depth-indicate-mode'.