Function call in default-frame-alist

[Sébastien Kirche]

Hi,
i defined the following to alter the geometry of new emacs frames (osx 
version):

 (if window-system
         (setq default-frame-alist '((width . 100)
                                                                 (height . 44)
                                                                 (top . 
50);pixels
                                                                 (left . 
50);pixels
                                                                 (font . 
"fontset-mac"))))

I would also like to set the truncate-line that is buffer dependant 
with (toggle-truncate-lines 1)

I didn't see any equivalent to defaukt-frame-alist (neither apropos, 
nor show variable or help function)...

How should i do ?
Thanks

Sébastien Kirche