Apart from the 7.5 option of the ISPF MENU.. you can even type WHO from the SDSF panel..
Also from the SPOOL, you can type this command....
/d prod, registered
This will list the version of the OS and the subsystems..
Note: For giving these commands.. you should have the privilege too. Usually the operator or SYSPMS will have the privilege.
I request all members to check the previous issues to find solutions, rather than simply posting the query. It is not productive and making this forum as more repetitions.