It is advisable to split up the system administration ID into TSOS and the default user ID because the number of system files which must be contained under TSOS amounts to several thousand. Without splitting, these catalog entries must also always be searched each time a user accesses $file.
System administration ID (TSOS)
All files required for maintaining system operation are cataloged under this ID. The user catalog, file catalog, logging file and accounting file, for example, are concerned here, but also all files which need to be accessed before SYSTEM READY.Default user ID
This ID is defined with the system parameter DEFLUID. All utility routines, language processors, libraries, etc. that are frequently needed by the user should be cataloged under this ID.
This parameter can also be used to specify a pubset. However, it is better to assign the standard pubset with the aid of the ADD-USER command.
Should the pubset with the user ID specified for DEFLUID become defective, a standby pubset can then be used. In this case only the user catalog entry of the user ID would have to be modified.
For the START-/LOAD-EXECUTABLE-PROGRAM, CALL-PROCEDURE, ENTER-PROCEDURE and ENTER-JOB commands the user should specify $filename instead of filename.
For instance, if START-EXECUTABLE-PROGRAM FROM-FILE=$EDT is entered, the user ID specified with DEFLUID is referenced immediately.
If START-EXECUTABLE-PROGRAM FROM-FILE=EDT is entered, a file with the name EDT is first searched for under the calling user ID, and then under the user ID specified with DEFLUID.The system administration should specify a suitable value for secondary allocation when the system is generated (system parameter DMSCALL), because the secondary allocation of storage space is very time-consuming as the corresponding catalog entry is changed with every user task request.
To prevent saturation of the public storage space it is advisable to release storage space not used by user files. The system administration can create procedures for this purpose. See section “Monitoring storage space saturation”