There are also several subsystem syntax files activated in addition to the basic syntax file. A subsystem syntax file contains the definitions of commands and programs that belong to a subsystem managed by DSSM or even to any installation unit (including BS2CP). Subsystem syntax files can be modified using SDF-A. Any such modifications, e.g. limitations on functional scope, apply for all users of the system.
The activation of a subsystem syntax file during the session takes immediate effect for all existing and future tasks.
There are two ways to activate subsystem syntax files:
The name of the subsystem syntax file was defined in the subsystem declaration. In this case the subsystem syntax file is automatically activated when the subsystem is loaded and deactivated when the subsystem is unloaded.
The name of the subsystem syntax file is entered in the SDF parameter file. In this case the subsystem syntax file is automatically activated at system initialization. If the pubset on which this file is stored is not available when the system is initialized, then it can only be activated after importing the pubset.
It can be modified (deactivated or exchanged) via the SDF parameter file only if the change is meant to be permanent. In this case, the subsystem syntax file is available independently of the availability of the corresponding subsystem.
If a command or statement definition is defined in more than one active subsystem syntax files, then the following cases arise:
Only one version of the subsystem can be active at a time. In this case the command or statement definition is used that is found in the syntax file of the version of the subsystem last activated.
Several versions of the subsystem can be active at a time (coexistence). The following cases arise:
The command or statement definition from the syntax file of the corresponding subsystem version is used for a task that is assigned to a specific subsystem version.
The syntax analysis of a START-<utility> command is always performed before the program is loaded, i.e. before connecting the task to a subsystem version of the program called. This is why the syntax file of the first version of the subsystem activated is evaluated.The command or statement definition contained in the first version of the subsystem activated is used for tasks that are not assigned to any subsystem version.