There is no command that will start all subsystems.
Just create a CL to start the ones you need started.
The system value QSTRUPPGM can be modified to call your program so with every IPL, all your subsystems will be started.
Depending on your configuration, if Qctl is the controlling subsystem, when you start Qctl all other subsystems will be started. I use
which starts Qctl and all of the other subsystems.
Hope this helps,
Just for detail — the STRSBS <controllingSubsystem> command doesn’t <i>necessarily</i> start all subsystems; that is the default behavior but not required. However, almost every site can expect it to work that way since nearly all sites follow the default configuration. Unless you have evidence to the contrary, you can assume that all normal subsystems will try to start.
Also, if the controlling subsystem is already active, then the STRSBS <controllingSubsystem> command should fail. (Of course, that would mean that the assumed conditions of the question don’t hold true — that <i>all</i> subsystems are in a not-started state.) If the controlling subsystem isn’t ended, you should be able to end it and then run STRSBS <controllingSubsystem> from the console or the HMC or whatever your system uses.