The Set Subsystem (SS) command sets the VTS subsystem name for subsequent tableBASE calls. All table access requests will be satisfied from the named VTS-TSR from this point on, until another SS command resets the subsystem name. This is a Driver-specific command; although it is not necessary in application programs using TBLBASE, it is required in the Driver to provide access to the TB-PARM parameter of TBLBASE calls.
Issuing an SS command with a blank subsystem name will reset subsequent tableBASE API calls to use the local TSR.