[Solved]-Utilizing full height in highcharts bubble chart-Highcharts

There are option to set the min/max bubble size. The default is that the max size is 20% of the hight of the chart. You can change this in plotOptions e.g.:

 plotOptions: {
        lineWidth: 0,
         bubble: {
                minSize:2,
                maxSize:"50%"
         }
    },

Note, you can also set the max as a number of pixels.