Db2 Communications Database Setup
Db2 for z/OS manages inbound and outbound security via a set of tables called the communications database (CDB). Inbound security validation for APPC/LU 6.2 DRDA clients is managed by the SYSIBM.LUNAMES table. To implement the simplest security model, enter a blank row in this table:
INSERT into SYSIBM.LUNAMES (LUNAME) VALUES (‘ ‘ );
When table SYSIBM.(SYS)LUNAMES contains a blank row, Db2 forwards the userid/password combination sent by the DRDA client (CONNX) to the system-installed security component, such as RACF, ACF/VTAM, or TopSecret.
For TCP/IP-based connections, the SYSIBM.(SYS)LUNAMES tables is bypassed, so you do not need to populate it.
This table represents sample output from SELECT * from SYSIBM.LUNAMES:

APPC Security | CONNX Option | Values sent from client to host
Same | UserID | UserID only.
Program | UserID & Password | User ID and password.
None | None | None, but Db2 for z/OS rejects this option.