{
   my $static;
   sub func {
      ...
   }
}
[download]

I'd updated that to:

BEGIN {
    my $static= ...;
    sub func {
        ...
    }
}
[download]

The BEGIN allows this to work just fine under mod_perl, and protects against people calling the subroutine before the $static is initialized. The subroutine is defined when it is compiled, so it is best to initialize the $static before that.