Using CSRF with AJAX Codeigniter Datatables

First of all I have to say sorry for my poor english...I hope to explain my issue and find a solution thanks to this community.
The issue: I'm not able to pass regenerated CSRF token to AJAX Datatables in Codeigniter.
The first loading table works fine but I get error trying to perform any Datatables action...like searching data, reordering column and so on...
The server PHP code...in the last rows..is the following:

        $csrf_name = $this->security->get_csrf_token_name();
        $csrf_hash = $this->security->get_csrf_hash();

        $json_data = array(
                    "draw"            => intval($this->input->post('draw')),
                    "recordsTotal"    => intval($totalData),
                    "recordsFiltered" => intval($totalFiltered),
                    "data"            => $data
                    );

        $json_data[$csrf_name] = $csrf_hash;

        echo json_encode($json_data);

As I wrote...the code works fine the first time...
Here you are the Javascript code:

```
//Ajax datatables
var table = $('#table').DataTable({
"processing": true, //Feature control the processing indicator.
"serverSide": true, //Feature control DataTables' server-side processing mode.
"responsive": true,
"autoWidth": false, // Make Datatable really responsive
"order": [[ 0, "asc" ]], //Initial order for registration column.
"stateSave": true, // Save user state
"lengthMenu": [[15, 25, 50, -1], [15, 25, 50, "All"]],
"responsive": true,
"searchHighlight": true,

// Load data for the table's content from an Ajax source
"ajax": {
    "url": url + '/ajax_list',
    "dataType": "json",
    "type": "POST",
    "data": {"csrf_test_name": token_value},
    complete: function(response) {
       var data  = JSON.parse(response.responseText).data;

       $.ajaxSetup({
            data: CsrfSecret
        });
    },

},
"columns": [
              { "data": "cbtid" },
              { "data": "contributer" },
              { "data": "images" },
              { "data": "date" },
              { "data": "action" },
           ] ,
"createdRow": function ( row, data, index ) {
    $('td', row).eq(4).attr('data-id', data.cbtid);
},
//Set column definition initialisation properties.
"columnDefs": [
{
    "targets": [ 4 ], //fifth column.
    "orderable": false, //set not orderable
    "searchable": false, //set not searchable
}],
dom: "Bfrtip",
buttons: [{
    extend: "copy",
    className: "btn-sm"
}, {
    extend: "csv",
    className: "btn-sm"
}, {
    extend: "excel",
    className: "btn-sm"
}, {
    extend: "pdf",
    className: "btn-sm"
}, {
    extend: "print",
    className: "btn-sm"
}],
"language": {
    "processing": "Loading. Please wait ..."
},

});

```

I'm trying to retrieve the csrf_name token value returned by the server to set the CSRF token for the next POST request, did several test using "complete" or "dataSrc" Datatables function but no way to read those variables to set the new token.
Thanks a lot for any help