By using the LOGAPPL operand on the definition statement for an LU, the LU can automatically initiate a session with a specific application program whenever the LU is activated. The application program can either be the program with which the LU ultimately initiates a session or an intermediary application program to which the LU is temporarily assigned. For application programs in another network, the network-qualified name can be specified on the LOGAPPL operand.

The application program to which an LU is automatically logged on is called its controlling application program. If the LU is passed to another application program, VTAM® automatically initiates a session with the controlling application program when that session is terminated. If the application program with which the LU is in session terminates that session and there is no controlling application program, the LU is available for session initiation.

Figure 1 shows a sample automatic logon session:

Figure 1. Automatic logon to A50ACCTS application program

APPLNODE VBUILD TYPE=APPL
A50ACCTS APPL   ATNLOSS=ALL,      ENABLE ATTN EXIT FOR ALL LU 6.2 SESSIONS
                APPC=YES,         ENABLE LU 6.2 SUPPORT
                PARSESS=YES,      ENABLE PARALLEL SESSION FOR LU 6.2 SUPPORT
                SECACPT=ALREADYV, ACCEPT ALREADY VERIFIED LU 6.2 CONVERSATIONS
                ACBNAME=ACCOUNTS  NETWORK LU NAME=A50ACCTS
                                  VTAM APPLICATION APPLID=ACCOUNTS
                ⋮

LC3270NS LBUILD                      LOCAL NON-SNA ATTACHMENT
LOC3277  LOCAL  CUADDR=00A,          CHANNEL UNIT ADDRESS
                TERM=3277,           TERMINAL TYPE
                ⋮
                DLOGMOD=S3270,       DEFAULT LOGON MODE TABLE ENTRY
                LOGAPPL=A50ACCTS     AUTOMATIC LOGON APPLICATION