CICS IPIC workload distribution

From 3.0.59.0, IBM z/OS Connect supports workload distribution of requests across a group of CICS® regions, by using a single connection reference.

You can configure a group of IPIC connections for a single connection reference to enable requests to be distributed across the group of connected CICS regions, in a round robin sequence. For example, for a connection group of 3 CICS regions, A, B, C, requests are distributed as follows: A, B, C, A, B, C,.....

There is also the option to specify a weighted distribution across the CICS regions. A weighted distribution is configured by specifying the relative number of requests to be sent to each connection in the group. For example, for a connection group of 3 CICS regions, A, B, C, with request ratios 4, 2, 3, requests are distributed as follows: A, B, C, A, B, C, A, C, A

For more information on configuring workload distribution with zosConnect-2.0, see Configuring IPIC workload distribution. For more information on configuring workload distribution with zosConnect-3.0, see Configuring IPIC workload distribution.

If a CICS connection is lost, that connection is removed from workload distribution until the connection is reestablished. z/OS® Connect attempts to reestablish the connection at a regular interval specified by the connectionRetryInterval attribute on the zosconnect_cicsIpicConnection element. This attribute is applicable only when the connection is in a connection group. If all connections have been lost and there is a request ready to be sent, an attempt is made to reestablish a connection immediately, without waiting for the connection retry interval to expire.

When a request fails because the CICS connection is lost during the request send, or a request is rejected because the connection is closing, the request is retried to another CICS region in the group.

A CICS connection reference, whether it is specified in the service archive file or overridden by a policy at run time, can reference either an individual connection that is defined by a zosconnect_cicsIpicConnection element or a connection group that is defined by a zosconnect_cicsConnectionGroup element. An IPIC connection element can be included in more than one connection group. An IPIC connection that is included in a group can also be referenced directly by a request, outside of workload distribution.

The following example demonstrates a weighted workload distribution across two LPARs combined with a round robin distribution across a set of 3 CICS regions on each LPAR.

<zosconnect_cicsConnectionGroup id="cicsConn" cicsConnectionRefs="lparA, lparB" connectionRatios="3,2"/>

<zosconnect_cicsConnectionGroup id="lparA" cicsConnectionRefs="cicsConnA, cicsConnB, cicsConnC"/>
<zosconnect_cicsConnectionGroup id="lparB" cicsConnectionRefs="cicsConnD, cicsConnE, cicsConnF"/>

<zosconnect_cicsIpicConnection id="cicsConnA" host="192.0.2.0" port="1110"/>
<zosconnect_cicsIpicConnection id="cicsConnB" host="192.0.2.1" port="1111"/>
<zosconnect_cicsIpicConnection id="cicsConnC" host="192.0.2.2" port="1112"/>
<zosconnect_cicsIpicConnection id="cicsConnD" host="192.0.2.3" port="2120"/>
<zosconnect_cicsIpicConnection id="cicsConnE" host="192.0.2.4" port="2121"/>
<zosconnect_cicsIpicConnection id="cicsConnF" host="192.0.2.5" port="2122"/>