32.6.5.3 Stack Buffer
The stack buffer displays a call stack, with one line for each
of the nested subroutine calls (stack frames) now active in the
program. See Backtraces.
The selected frame number is displayed in reverse contrast. Move
point to any frame in the stack and type <RET> to select it
(gdb-frames-select
) and display the associated source in the
source buffer. Alternatively, click Mouse-2 on a frame to
select it. If the locals buffer is displayed then its contents update
to display the variables that are local to the new frame.