# test.pl
#/usr/bin/perl

use strict;
use warnigns;
BEGIN {
  use FindBin qw($RealBin);
  use lib "$RealBin/lib/";
  $ENV{APP_ROOT} = $RealBin;
}
use MyApp::Conf qw/APP_NAME/;
...
...

##</code><code>##

package MyApp::Conf;

BEGIN { # do something with $ENV{APP_NAME} }