Simple sample for looping a list with a caml query for a list with more than 5000 items.

SharePointCSOMQueryLargeLists.cs

List list = _ctx.Web.Lists.GetByTitle(Constants.Listnames.DocumentHistoryList);
_ctx.Load(list);
_ctx.ExecuteQueryRetry();

ListItemCollectionPosition collectionPosition = null;

CamlQuery query = new CamlQuery();

query.AllowIncrementalResults = true;

query.ViewXml =
  "<view Scope='RecursiveAll'>" +
    "<Query>" +
      "<Where>" +
        "<Eq>" +
          "<FieldRef Name='WorkflowID' />" +
          "<Value Type='Text'>4def8543-99a2-4239-88df-e4fe7298c646</Value>" +
        "</Eq>" +
      "</Where>" +
    "</Query>" +
    "<RowLimit Paged='TRUE'>500</RowLimit>" +
  "</View>";

do
{
  query.ListItemCollectionPosition = collectionPosition;

  ListItemCollection items = list.GetItems(query);
  _ctx.Load(items);
  _ctx.ExecuteQueryRetry();

  if (items != null)
  {
    collectionPosition = items.ListItemCollectionPosition;

    if (items.ServerObjectIsNull == false)
    {
      if (items.Count > 0)
      {
        foreach (ListItem item in items)
        {
          // do anything with the listitem
        }
      }
    }
  }
  else
  {
    collectionPosition = null;
  }
}
while (collectionPosition != null);