System Data File Classes

Like spool files, system data files have classes. However, these classes do not associate the files with particular real or virtual devices, but to indicate the state of the system data file.

A system data file's class may be one of the following:

A: Class A system data files are available for use. This class applies to all system data files except UCR files. Class A NSSs or saved segments have been defined and saved, class A image libraries are available for use by real printers, class A message repository files are available for use, and class A system trace files can be processed.
D: Class D applies to UCR and dump files. UCR files are not supported and no longer processed by CP.
I: Class I applies only to UCR files. UCR files are not supported and no longer processed by CP.
R: Class R applies only to NSSs, saved segments, and segment spaces. It indicates that the file is available but its use is restricted to one or more authorized virtual machines. In order to gain access to a restricted system data file, a virtual machine's z/VM directory entry must contain a NAMESAVE statement for the NSS or saved segment.
P: A class P system data file is in the pending purge state, which indicates that it will be purged either when the last virtual machine releases it or during the next system IPL or restart. This class applies only to NSSs, saved segments, and message repository files. CP purges image libraries, UCR files, and system trace files immediately.
S: Class S also applies only to NSSs and saved segments and indicates that the file is in the skeleton state. This means that the NSS or saved segment has been defined by way of a DEFSYS or DEFSEG command, but it has not yet been saved by way of a SAVESYS or SAVESEG command.
W: Class W applies only to system trace files. It indicates that a trace is active and that CP is currently writing trace data to the set of files associated with that trace.

A system data file class is assigned to a system data file when it is created and CP changes the system data file's class to match its state, as needed. For example, when a class E user enters a DEFSYS command to define an NSS, CP assigns class S to the newly-defined NSS file. After the user has IPLed the system to be named and saved and has entered the SAVESYS command, CP assigns class A or R to the completed NSS file. The NSS is now available to be used by one or, if shared, more users. If the class E user enters a PURGE command to remove a shared NSS from the system, but it is still in use by other users, CP marks the file as pending-purge and assigns class P to the file. When the last user releases the NSS from use, the file is purged.