The purpose of dynamic subsystem management (DSSM) is to reduce the complexity of BS2000 execution by dividing the operating system into functional units (subsystems).
Subsystems have the following features:
each subsystem constitutes a self-contained unit
subsystems can be activated, suspended, resumed and deactivated during the BS2000 session
If a new version has been created for a subsystem, the old version can be exchanged for the new one or both versions can be operated in parallel.
DSSM is the central facility for BS2000 subsystem configuration management. DSSM controls the loading, initialization, suspension, resumption and termination of subsystems during the session. DSSM can modify the current system dynamically (on-line) by incorporating subsystems in the subsystem catalog or removing them from it, without having to suspend and restart the system as a whole.
DSSM is mandatory for BS2000 since important components of the basic configuration (see Overview of important DSSM-compatible products in the BS2000 basic configuration) can be operated only with DSSM.
For information on the compatibility and portability of DSSM with regard to SSCM and BS2000, see Version dependencies between BS2000 OSD/BC, DSSM and SSCM.
DSSM command privileges
As part of the BS2000 privilege concept, a system-global privilege for execution of DSSM commands exists. The privilege to carry out subsystem management is referred to in commands and messages as SUBSYSTEM-MANAGEMENT. This privilege is allocated by default to the TSOS user ID after first startup. However, when SECOS is being used, the privilege can be assigned to any desired user ID; this user ID will then have the sole authority to issue these commands for execution (see also the “SECOS” manual [33]).
The following table contains an overview of all DSSM commands and the privileges required for command execution.
Command | Meaning | Required privilege | |||
SM | O | STD | HM | ||
ADD-SUBSYSTEM | Extend dynamic subsystem catalog | X | |||
HOLD-SUBSYSTEM | Place a subsystem in wait state | X | X | ||
MODIFY-SUBSYSTEM- | Modify subsystem parameters | X | |||
RELEASE-SUBSYSTEM-SPACE | Release reserved address space for subsystems | X | X | X | |
REMOVE-SUBSYSTEM | Remove inactive subsystem from dynamic catalog | X | |||
RESUME-SUBSYSTEM | Cancel wait state for subsystem | X | X | ||
SAVE-SUBSYSTEM-CATALOG | Save changes to dynamic subsystem catalog | X | |||
SET-DSSM-OPTIONS | Activate/deactivate DSSM logging function | X | X | ||
SHOW-DSSM-INFORMATION | Show information on DSSM | X | |||
SHOW-RESTART-OPTIONS | Display information on automatic restart | X | |||
SHOW-SUBSYSTEM- | Request information on subsystem attributes | X | X | ||
SHOW-SUBSYSTEM-INFO | Request information on current subsystems configuration | X | |||
SHOW-SUBSYSTEM-STATUS | Request information on status of subsystems | ||||
subsys=*NON-PRIV-CLASS-5 | X | X | X | ||
subsys=*ALL / <subsys-name> | X | ||||
START-SUBSYSTEM | Activate subsystem | X | X | ||
STOP-SUBSYSTEM | Deactivate subsystem | X | X | ||
UNLOCK-SUBSYSTEM | Shift subsystem from LOCKED status to NOT-CREATED status | X | |||
Table 3: DSSM commands and required privileges
SM: SUBSYSTEM-MANAGEMENT privilege for managing subsystems
O: OPERATING privilege for entry from operator terminals
STD: STD-PROCESSING privilege for executing user commands
HM: HARDWARE-MAINTENANCE privilege for calling hardware test programs