OpenLayers dynamic zoom levels

Question

In my application i add layers dynamically. The first added layer is a baseLayer. When i add layer i extend bounds so the new layer could fit map (it works). The problems is that i don't know how to recalculate zoom levels. In my map config i have maxResolution set to auto and the zoomLevel is set to 0. When i add map with bigger extent the zooms are not recalculated, so i cannot see whole layer. I use GeoExt framework with OL. Code:

addLayer:function(record) {

        var layer = _factoryManager.getFactory('layer').getLayer(record, this.getServiceType());

        var map = this.getActiveMap().map;

        map.addLayer(layer);
        console.log('adding layer');
        //console.log(map.getZoomForExtent(map.maxExtent));
        //console.log(map.getZoom());
        map.maxExtent.extend(this.calculateBounds(layer));
        //console.log(map.getZoomForExtent(map.maxExtent));
        //console.log(map.getZoom());
        this.zoomToLayer(layer);
    },

And map creation:

map = Ext.create('OGC.core.panel.MapPanel',{
            map: {
                controls: controls,
                //allOverlays: true, if nothing specified all overlays is set to true
                scope:this,
                projection:this.getCRS(),
                maxExtent:bounds, 
                maxResolution:"auto",
                //allOverlays: false,
                eventListeners:{
                    zoomend:function(evt){
                        console.log(this);
                        console.log('zoomend');
                        console.log(this.getZoom())
                        console.log(this.getScale());
                        Ext.getCmp('map-bottom').update('Scale: ' + this.getScale());
                    }
                }
            },
            layers: [layer]
        });