Setting Db2 for z/OS subsystem parameters for Data Gate

Set the following Db2 subsystem parameters:

ACCEL

Set this subsystem parameter to the value AUTO (ACCEL=AUTO). This means that Data Gate is started automatically by Db2 for z/OS.

Important: After the Data gate instance is created and paired to a Db2 zOS, the related accelerator status is not 'STARTED' by default. The accelerator starts during the next Db2 zOS restart. If you want to see monitoring messages such as DSNX881I in MVS syslog before the next Db2 zOS restart, use the command -DISPLAY ACCEL(*) to check the accelerator status, and then use the command -START ACCEL(accelerator name) to start it if the status is not 'STARTED' in the MVS console. If Db2 for z/OS is a data sharing system, add "SCOPE(GROUP)" in the DISPLAY and START commands as follows:

-DISPLAY ACCEL(*) SCOPE(GROUP)
-START ACCEL(accelerator name) SCOPE(GROUP)

AUTH_COMPATIBILITY

Set this subsystem parameter to SELECT_FOR_UNLOAD to ensure proper privileges for the initial load of data into Data Gate.

CMTSTAT

Set this to CMTSTAT=INACTIVE, which is also the default. So, you must change the parameter value just in case the current value is ACTIVE. You need not change the setting if the parameter is not set at all.

The CMTSTAT subsystem parameter controls whether in-use database access threads (DBATS) can be pooled, for use by other connections, after they successfully commit or roll back. For more information, see DDF THREADS field (CMTSTAT subsystem parameter).

The setting CMTSTAT=ACTIVE is rarely used these days and has not been recommended for a long time. In the past, a performance improvement might be achieved by using it in a controlled environment with a fixed (known) number of connections.

However, the use of this setting leads to a drawback if the number of connections varies. To restrict or control the number of connections, you need to set the MAXDBAT parameter, which defines a maximum for the number of connections. For example, if you want 10000 client connections, you must set MAXDBAT to 10000. The use of such a limit is resource-intensive.

Another drawback is that HTTP sessions cannot be reused. This means that every HTTP request requires an SSL handshake. This is true for both, the HTTP application programming interface (API) and the log reader API of Db2 for z/OS. The higher demand for SSL handshakes binds AT-TLS resources unnecessarily.

TCPKPALV

Set this parameter to the integer value 120 or ENABLE. The value 120 is also the default. The value ENABLE means that the TCP/IP KeepAlive configuration value is used and not overridden with the TCPKPALV value instead (see the TCPCONFIG code sample). Change the parameter value just in case that it is set to DISABLE. You need not change the setting if the parameter is not set at all.

The TCPKPALV subsystem parameter determines whether the TCP/IP KeepAlive value in the TCP/IP configuration is to be overridden with a different value. For more information, see TCP/IP KEEPALIVE field (TCPKPALV subsystem parameter)

POOLINAC

Set this parameter to the integer value 120, which is also the default. So, you must change this parameter just in case it is set to a different value. You need not change the setting if the parameter is not set at all.

The POOLINAC subsystem parameter specifies the approximate time, in seconds, that a database access thread (DBAT) can remain idle in the pool before it is terminated. For more information, see POOL THREAD TIMEOUT field (POOLINAC subsystem parameter)