@avb,
As mentioned in the previous reply, you can enable zooming in the individual charts of stockchart by setting zoomEnabled to true. Please take a look at code snippet below.
.
.
.
charts: [{
  zoomEnabled: true,
  axisX: {
    crosshair: {
      enabled: true,
      valueFormatString: "MMM DD, YYYY HH:mm:ss"
    }
  }
.
.
.
Also check out this updated JSFiddle for the example.
—
Manoj Mohan
Team CanvasJS