The source code

    /**
     * @class Ext.StoreMgr
     * @extends Ext.util.MixedCollection
     * The default global group of stores.
     * @singleton
     */
    Ext.StoreMgr = Ext.apply(new Ext.util.MixedCollection(), {
        /**
         * @cfg {Object} listeners @hide
         */

        /**
         * Registers one or more Stores with the StoreMgr. You do not normally need to register stores
         * manually.  Any store initialized with a {@link Ext.data.Store#storeId} will be auto-registered.
         * @param {Ext.data.Store...} stores Any number of Store instances
         */
        register : function(){
            for(var i = 0, s; (s = arguments[i]); i++){
                this.add(s);
            }
        },

        /**
         * Unregisters one or more Stores with the StoreMgr
         * @param {String/Object} ids IDs of the Stores, or Store instances
         */
        unregister : function(){
            for(var i = 0, s; (s = arguments[i]); i++){
                this.remove(this.lookup(s));
            }
        },

        /**
         * Gets a registered Store by id
         * @param {String/Object} id The id of the Store, or a Store instance
         * @return {Ext.data.Store}
         */
        lookup : function(id){
            if(Ext.isArray(id)){
                var fields = ['field1'], expand = !Ext.isArray(id[0]);
                if(!expand){
                    for(var i = 2, len = id[0].length; i <= len; ++i){
                        fields.push('field' + i);
                    }
                }
                return new Ext.data.ArrayStore({
                    fields: fields,
                    data: id,
                    expandData: expand,
                    autoDestroy: true,
                    autoCreated: true

                });
            }
            return Ext.isObject(id) ? (id.events ? id : Ext.create(id, 'store')) : this.get(id);
        },

        // getKey implementation for MixedCollection
        getKey : function(o){
             return o.storeId;
        }
    });