To have a value persist between invocations of a subroutine, you can use a variable that exists outside the scope of the subroutine. There are various ways to do this, one of which is as follows. I added a limit on recursion.

use strict;
use warnings;

testFunc();

{
    my $i = 0;

    sub testFunc {
        $i++;
        print "$i\n";
        testFunc() if($i <10);
    }
}
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