The first use has gradually been supplanted by COMMAREA and other CICS facilities, but the second is still fairly common. An application may store statistics, such as teller totals, in the TCTUA, which is initialized by a PLTPI program at the beginning of execution and retrieved by a PLTSD program at termination (shutdown). Autoinstall does not provide the ability to save this information between logoff and logon, because the TCTUA does not exist then. In addition, the TCTUA is not available to PLTPI and PLTSD programs at system initialization and termination. A new technique must be devised to allow the initialization of TCTUA and user data when the user logs on or logs off.
As noted earlier, the autoinstall process creates the TCT entry (including the TCTUA) before the first transaction is executed at the terminal, but after the autoinstall control program has done its initial execution. Thus you cannot access the TCTUA in the autoinstall control program and so any TCTUA initialization must be done later. You could write your own 'good morning' transaction to do this, or use the first transaction of the application in question.
Furthermore, the autoinstall control program does not have access to the TCTUA at logoff either, because CICS deletes the TCT entry (including the TCTUA) before invoking this program. Therefore, if an application needs to capture statistics or other information from such a TCTUA, it must get access before CICS does this. The place to do this is in the node error program (NEP), the user-written component of the terminal error processing routines, because CICS drives the NEP exit before it deletes the TCT entry.