To make a column or bar series stacked, you do:
$series->Stacked = TRUE;//default = FALSE
<?php
$KoolControlsFolder = "../../../../KoolControls";//Relative path to "KoolPHPSuite/KoolControls" folder
require $KoolControlsFolder."/KoolChart/koolchart.php";
$chart = new KoolChart("chart");
$chart->scriptFolder=$KoolControlsFolder."/KoolChart";
$chart->Title->Text = "Sales report for 2012";
$chart->Width = 680;
$chart->Height = 500;
$chart->PlotArea->XAxis->Title = "Quarters";
$chart->PlotArea->XAxis->Set(array("Q1","Q2","Q3","Q4"));
$chart->PlotArea->YAxis->Title = "Sales ( .millions)";
$chart->PlotArea->YAxis->LabelsAppearance->DataFormatString = "$ {0}";
$series = new ColumnSeries();
$series->Stacked = TRUE;
$series->Name = "TVs";
$series->TooltipsAppearance->DataFormatString = "$ {0} millions {1}";
$series->ArrayData(array(20,30,40,70));
$chart->PlotArea->AddSeries($series);
$series = new ColumnSeries();
$series->Stacked = TRUE;
$series->Name = "Computers";
$series->TooltipsAppearance->DataFormatString = "$ {0} millions {1}";
$series->ArrayData(array(34,55,10,40));
$chart->PlotArea->AddSeries($series);
$series = new ColumnSeries();
$series->Name = "Tablets & e-readers";
$series->TooltipsAppearance->DataFormatString = "$ {0} millions {1}";
$series->ArrayData(array(56,23,56,80));
$chart->PlotArea->AddSeries($series);
$chart2 = new KoolChart("chart2");
$chart2->scriptFolder=$KoolControlsFolder."/KoolChart";
$chart2->Title->Text = "Sales report for 2012";
$chart2->Width = 680;
$chart2->Height = 480;
$chart2->Legend->Appearance->Position = "top";
$chart2->PlotArea->XAxis->Title = "Quarters";
$chart2->PlotArea->XAxis->Set(array("Q1","Q2","Q3","Q4"));
$chart2->PlotArea->YAxis->Title = "Sales (millions)";
$chart2->PlotArea->YAxis->LabelsAppearance->DataFormatString = "$ {0}";
$series = new BarSeries();
$series->Stacked = TRUE;
$series->Name = "TVs";
$series->TooltipsAppearance->DataFormatString = "$ {0} millions {1}";
$series->ArrayData(array(20,30,40,70));
$chart2->PlotArea->AddSeries($series);
$series = new BarSeries();
$series->Stacked = TRUE;
$series->Name = "Computers";
$series->TooltipsAppearance->DataFormatString = "$ {0} millions {1}";
$series->ArrayData(array(34,55,10,40));
$chart2->PlotArea->AddSeries($series);
$series = new BarSeries();
$series->Stacked = TRUE;
$series->Name = "Tablets & e-readers";
$series->TooltipsAppearance->DataFormatString = "$ {0} millions {1}";
$series->ArrayData(array(56,23,56,80));
$chart2->PlotArea->AddSeries($series);
?>
<form id="form1" method="post">
<div>
<?php echo $chart->Render();?>
</div>
<div>
<?php echo $chart2->Render();?>
</div>
<div><i>* <u>Note</u>:</i>Generate your own chart with <a style="color:#B8305E;" target="_blank" href="http://codegen.koolphp.net/generate_koolchart.php">Code Generator</a></div>
</form>