RE: bundling C-u C-space

[Drew Adams]

> > I'd like to get the functionality of Control-u Control-space in
> > one keystroke (for instance, Control-,)
> 
> (global-set-key (kbd "C-,") 'pop-to-mark-command)

BTW, you could discover `pop-to-mark-command' (it is not mentioned
in the manual) this way:

C-h k C-@
tells you that that command is `set-mark-command'.

Click the link in buffer *Help* that takes you to the command
definition in `simple.el'.

M-x debug-on-entry set-mark-command

C-u C-@

and walk through the debugger, to see what functions are used
to provide the behavior.  You'll see that only function
`pop-to-mark-command' is invoked.

It's name suggests that it might be a command, but
`C-h f pop-to-mark-command' confirms this.  It is all you need.