for calculating the percentage of height  we need the parent view right ? 
which we use other than this ?

me use the test case bellow that is working fine 

var win=Ti.UI.createWindow();
var tableview=Ti.UI.createTableView({
    backgroundColor:'blue'
});
var tableviewrow=Ti.UI.createTableViewRow({
    height:'50%',
    backgroundColor:'red'
});
var btn = Ti.UI.createButton({
title : '100 %',
 height:'100',
 width : '150' ,  top : '110'
 
});
 

var btn1 = Ti.UI.createButton({
title : '25 %',
 height:'100',
 width : '150' , top : '10'
 
});
 var btn300 = Ti.UI.createButton({
title : '300',
 height:'100',
 width : '150' ,  top : '210'
 
});
tableview.setData([tableviewrow]);
win.add(tableview);
win.add(btn);
win.add(btn1);
win.add(btn300);
btn.addEventListener('click', function() {
	// Check console
	 tableviewrow.height = '100%'
	});
	btn1.addEventListener('click', function() {
	// Check console
	 tableviewrow.height = '25%'
	});
btn300.addEventListener('click', function() {
	// Check console
	 tableviewrow.height = '300'
	}); 
win.open();