$compile_dir
This is the name of the directory where compiled templates are
located. By default this is
./templates_c, meaning that Smarty
will look for the templates_c/
directory in the same directory as
the executing php script. This directory must
be writeable by the web server,
see install for more info.
Technical Note:
This setting must be either a relative or
absolute path. include_path is not used for writing files.
Technical Note:
It is not recommended to put this directory under
the web server document root.
See also $compile_id
and
$use_sub_dirs.