The stacked volume is used to identify the media that is used for the export container volume, to track its location, and to aggregate the logical volumes contained in the volume. All movement for exported logical volumes is managed and tracked using the stacked volume. You can move a stacked volume manually, but normally you control the movement automatically using vital record specifications. The vital record specifications identify movement for data sets on logical volumes. The movement specified for the logical volumes in the stacked volume container direct the movement of the stacked volume. DFSMSrmm automatically defines stacked volumes at EXPORT time. DFSMSrmm keeps track of the "in container" information only while the logical volume is exported.