LinkButton OnClick GridView PageSize

I'm trying to change Gridview Pagesize on LinkButton click event:
<div id="totalItems" runat="server" style="border: 1px solid #c1c1c1; font-weight:bold; padding:5px"></div> <div>Display <asp:LinkButton id="items16" Text="16" runat="server" OnClick="DisplayResults_Click" CommandName="16" /> | <asp:LinkButton id="items32" Text="32" runat="server" OnClick="DisplayResults_Click" CommandName="32"/> | <asp:LinkButton id="items56" Text="56" runat="server" OnClick="DisplayResults_Click" CommandName="56"/> results per page</div> <br /> <asp:GridView ID="grdItems" runat="server" AutoGenerateColumns="false" OnRowCommand="grdItems_RowCommand" OnRowDataBound="grdItems_DataBound" He ...