When to add manual locks
Under normal circumstances, you do not need to set manual locks because there are already internal locks set; however, in some circumstances, manual locks are necessary. For example, when using a mainframe system and a Telnet connector with no inherent locks, your mainframe target system may limit the target system administrator to have only one login at a time. In this situation, you need to set a manual lock so you do not attempt to have two login sessions using the same administrator ID simultaneously.
Warning
The arbitrary use of manual locks may interfere with internal locking behavior.