startValue: Number

Sets the point where the stripLine’s shaded region begins on the y-axis. Should be used along with endValue.

var  chart =  new  CanvasJS.Chart("container",
{
 .
 .
axisY:{
    stripLines: [{
        .
        startValue:20,
        endValue:25,
        .
    }]
},
 .
 .
});
chart.render();