The integrated file system is a part of the i5/OS™ program that supports stream input/output and storage management similar to personal computers and UNIX® operating systems. The integrated file system also provides an integrating structure over all information that you store in the server.
You can view all objects on the server from the perspective of a hierarchical directory structure. However, in most cases, you view objects in the way that is most common for a particular file system. For example, you usually view objects in the QSYS.LIB file system from the perspective of libraries. You usually view objects in the QDLS file system as documents within folders.
Similarly, you should save objects in different file systems with the methods that are designed for each particular file system. You can find several good examples of how to use the SAV command in the CL reference information in the Information Center.