Logon

Logging on is how you start work. You connect to the system with a terminal emulator, reach a logon screen, and enter a user ID and a password or password phrase.

Mainframe user IDs are short, typically up to eight characters, and are often built from your name or a team convention. Unlike an email address, the same person may have different IDs on the development, test and production systems, because those are separate systems with separate security databases.

What you can do once you are on is decided entirely by that ID. It determines which datasets you can read or change, which transactions you can run and which commands you are allowed to issue. Access is granted through the security manager, usually RACF, by adding your ID to groups rather than by listing you individually against every resource.

Sessions are usually limited to one per user per system, so logging on somewhere else can disconnect you, and idle sessions are often timed out automatically.