ExtJS DirectStore设置参数值

在EXTJS DirectStore中，我想设置参数vaule，然后重新加载它。怎么做

var myStore = new Ext.data.DirectStore({
            directFn: Report.ReadReport,
            autoLoad: false,
            paramsAsHash: false,
            paramOrder: 'identifier',
            root: 'Report',
            totalProperty: 'total',
            fields: [
                { name: 'name', type: 'string' }
                ],
            remoteSort: true,
            listeners: {
                load: function (store, recs, opt) {
                    myGrid.setHeight(400);
                    myGrid.doLayout();
                }
            }
        });

我想要的是这样

myStore.param.'identifier'.value = '12345'
myStore.load();

怎么做？可能吗

谢谢

myStore.load({
    params: {
        identifier: 12345
    }
});