my %controlCentre=();

$controlCentre{ FH } = [];
$controlCentre{ DH } = [];

Traverse( tree => 'whatever-path',
          control => \%controlCentre );

sub Traverse{
    my %par = (@_);
    my $dh = OpenDir(dir=>$par{ tree },
                     control=>$par{control});
    foreach my $file ( grep !/^\./, readdir $dh ) {
        my $path = "$par{tree}/$file";
        if ( -d $path ) {
            Traverse( tree => $path,
                      control => $par{ control }
                    );
        else {
            ProcessFile( name => $path,
                         control => $par{ control } );
        }
    }
    CloseDir( dh => $dh, control => $par{ control });
}

sub ProcessFile{ 
    my %par =(@_);
    my $fh = Open( cmd => "<$par{name}",
                   control =>$par{control} );
    # ...
    # process <$fh> here with any recursive calls
    # to ProcessFile that may be required
    #...

    Close( control => $par{ control } ),
           fh=>$fh );
}

sub Open{
    my %par = (@_);
    open my $fh, $par{ cmd };
    my $aref=$par{ control } -> { FH };
    push @$aref, $fh;

    # N.B. $#$aref is now one less than
    # the count of open files

    return $fh;
}

sub Close{
    my %par = (@_);
    close $par{ fh };
    my $aref = $par{ control } -> { FH };
    my $fh = pop @$aref;
    ( $fh eq $par{ fh } )
        or die "fh stack was abused: "
             . "$fh does not match $par{ fh }";
}

sub OpenDir{
    my %par = (@_);
    opendir my $dh, $par{ dir };
    my $aref=$par{ control } -> { DH };
    push @$aref, $dh;
    return $dh;
}

sub CloseDir
    my %par = (@_);
    closedir $par{ dh };
    my $aref = $par{ control } -> { DH };
    my $dh = pop @$aref;
    ( $dh eq $par{ dh } )
        or die "dh stack was abused: "
             . "$dh does not match $par{ dh }";
}