#1. export a global sharable variable
  require Exporter;
  our @ISA = qw/Exporter/;
  our @EXPORT = qw/%GV/;
  our %GV = (....);

#2. add more Lib path
  push @INC, "D:/Lib/$ENV{SERVER_NAME}"
    if ($ENV{REMOTE_ADDR}) ;

#3. define some dynamic path
  $ENV{MyData} = "D:/UsrData/Guest/";
  $ENV{MyData} = "D:/UsrData/$ENV{USER}"
    if (length $ENV{USER});