Highcharts fix plotlines threshold show very near at bottom of the container

Question

I'm using react with chart type is stockChart, 2 series line and area. The threshold line (yellow line) show very near at bottom of the container. How can I config in any case threshold line will not show very near at top and bottom of chart container ?

Tks for your help. img

plotOptions: {
column: {
    maxPointWidth: 2
},
series: {
    fillOpacity: 0.1,
        marker: {
        enabled: false,
            states: {
            hover: {
                enabled: false
            }
        }
    },
    shadow: false,
        dataGrouping: {
        enabled: false
    },
    stacking: 'normal',
        negativeColor: '#ea3943',
            lineWidth: 1,
                states: {
        hover: {
            lineWidth: 1
        },
        inactive: {
            opacity: 1
        }
    },
    pointPadding: 0,
        groupPadding: 0.1
},
area: {
    fillOpacity: 0.6
}

}