Barline type before \time change

[Urs Liska]

Hello list,

I'm sorry, but I can't find the relevant documentation.
I want to change lilyPond's default behaviour and tell it to use "||" 
barlines before \time changes instead of normal ones.
Although it is quite easy to do this manually, I'd like to know where 
and how I could change this setting, possibly in a \layout section.

Best
Urs