How to set height on canvas after filled some text?

I'm filling canvas with some dynamic texts in ArrayList. And I set the height as length of ArrayList like ArrayList.length * 20 or something like that.

HTML:

<canvas id="myCanvas" width="272px" style="border: 1px solid black"></canvas>

JS :

var canvas = document.getElementById("myCanvas");
var context = canvas.getContext("2d");
var myheight = 10;
for(var i = 0; mylist.length > i; i++){
     context.fillText("my text", 10, myheight);
     myheight += 10;
}

loop works fine, texts are filled.. and I'm trying to calculate the canvas.height after the loop.

When I set canvas.height = myheight and all filled texts are gone.. canvas gone blank.

How can I set height after canvas filled by texts dynamically?

Help me.. Thank you.. And sorry for bad English..