charts is a collection of chart options that allows you to set data and all attributes / properties of Charts to be displayed inside the StockChart. A Chart is created for each chart options object that you add to this array.
var stockChart = new CanvasJS.StockChart("container",
{
.
.
charts: [
{// chart options 1
},
{// chart options 2
}
}],
.
.
});
stockChart.render();
Please refer to chart options page for more information about the attributes / properties available.
Also See: