#!/usr/bin/perl -w

use feature qw{ state };
use strict;
use warnings;

for (1..5) {
    some_sub();
}

sub some_sub {
    (state $b_initialized++) or initialize();
    print "Now doing the main work of some_sub() ...\n";
}


sub initialize {
    print "Initializing....\n";
    # ... etc ...
}

__END__

=== Output ===

Initializing....
Now doing the main work of some_sub() ...
Now doing the main work of some_sub() ...
Now doing the main work of some_sub() ...
Now doing the main work of some_sub() ...
Now doing the main work of some_sub() ...