Did not misconstru anything, I searched through all 966 posts but found no help except did confirm that "parses the entire spreadsheet document into memory."

No where in the 966 posts was it said that rows and columns are in sequence when passed through the cell_handler

I experimented and confirmed, perl does not release memory to a free pool on undef of the Spreadsheet::ParseExcel object reference. So, the memory used during the parse process is sitting there unused and un-allocatable to other variables.

 
my $cell_outputfh;
for (my $i=0;$i <  scalar(@workbook_zip_FNS) ;$i++ ) {

    my $xls_parser   = Spreadsheet::ParseExcel->new(
        CellHandler => \&HH_cell_handler,
        NotSetCell  => 1
    );

    open ( $cell_outputfh, ">:encoding(iso-8859-1)", $ribbon_srcgeo[$i
+].".csv" )  or  die " open failed on $ribbon_srcgeo[$i].csv $!";
    my $workbook = $xls_parser->parse($unzipped_xls_FNS[$i]);
    if ( !defined $workbook ) { die $xls_parser->error(), ".\n"; }
    print "\n";
    close $cell_outputfh;

    my @wsnames;
    my @row_mins;
    my @row_maxs;
    my @col_mins;
    my @col_maxs;
    for my $worksheet ( $workbook->worksheets() ) {
        push @wsnames, $worksheet->get_name();
        my ( $row_min, $row_max ) = $worksheet->row_range();
        my ( $col_min, $col_max ) = $worksheet->col_range();
        push @row_mins, $row_min;
        push @row_maxs, $row_max;
        push @col_mins, $col_min;
        push @col_maxs, $col_max;
    }
    undef $workbook;
    undef $xls_parser;

    for (my $j=0;$j <  scalar(@wsnames) ;$j++ ) {
        print $wsnames[$j]."*";
        open ( $cell_outputfh, "<:encoding(iso-8859-1)", $ribbon_srcge
+o[$i].".csv" )  or  die " open failed on $ribbon_srcgeo[$i].csv $!";
        my %HofA_sheet_cells;
        # make has out of cells
        while (<$cell_outputfh>) {
            my @fields = split /","/, $_;
            $fields[0] =~ s/^"//;
            $fields[3] =~ s/"$//;

            if( $fields[0] eq $wsnames[$j] ) {
                $HofA_sheet_cells{$wsnames[$j]}[$fields[1]][$fields[2]
+] = $fields[3];
                $dot_ctr++;
                if ( $dot_ctr == 1000) {
                    $| = 1;             #flush the buffer
                    print "*"; $dot_ctr=0;
                }
            }
        }
        undef %HofA_sheet_cells;
        close $cell_outputfh;
    }
}
sub HH_cell_handler {

    my $workbook    = $_[0];
    my $sheet_index = $_[1];
    my $row         = $_[2];
    my $col         = $_[3];
    my $cell        = $_[4];

    my $worksheet = $workbook->worksheet($sheet_index);
    my $wsname=$worksheet->get_name();
    my $value='"'.$wsname.'"'.','.'"'.$row.'"'.','.'"'.$col.'"'.','.'"
+'.$cell->value().'"'."\n";
    print $cell_outputfh $value;
}
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