The LUname (terminal) relation

When you define an affinity relation of LUname to a transaction group, all instances of all the transactions in the group that are associated with the same terminal must run in the same target region for the lifetime of the affinity.

If the affinity relation is LUname , the affinity lifetime must have one of the following values:
Pseudoconversation
The affinity lasts for the whole pseudoconversation, and ends when the pseudoconversation ends at the terminal. Each transaction must end with EXEC CICS RETURN TRANSID, not with the pseudoconversation mode of END.
Logon
The affinity lasts for as long as the terminal remains logged on to CICS, and ends when the terminal logs off.
System
The affinity lasts for as long as the target region exists, and ends whenever the target region terminates (at a normal, immediate, or abnormal termination).
Permanent
The affinity extends across all CICS restarts. If you are running CICSPlex® SM , this affinity lasts for as long as any CMAS involved in managing the CICSplex using the workload is active.
Delimit
The affinity continues until a transaction with a pseudoconversation mode of END is encountered.
A typical example of transactions that have an LUname relation are those that:
  • Use a local TS queue to pass data between the transactions in a pseudoconversation, and
  • Use a TS queue name that is derived, in part, from the terminal name (see Avoiding affinities when using temporary storage for information about TS queue names).

These types of transactions can be placed in an affinity group with a relation of terminal and a lifetime of pseudoconversation. When the dynamic routing program detects the first transaction in the pseudoconversation initiated by a specific terminal ( LUname ), it is free to route the transaction to any target region that is a valid candidate for that transaction. However, any subsequent transaction in the affinity group that is initiated at the same terminal must be routed to the same target region as the transaction that started the pseudoconversation. When the affinity ends (at the end of the pseudoconversation on a given terminal), the dynamic routing program is again free to route the first transaction to any candidate target region.

This form of affinity is manageable and does not impose too severe a constraint on dynamic transaction routing, and might occur in many CICSplexes. It can be managed easily by a dynamic routing program, and should not inhibit the use of dynamic routing.

Figure 1 shows this type of example.
Figure 1. Managing inter-transaction affinity with LUname relation and pseudoconversation lifetime
An example showing transaction AAAA from terminal with LUNAME IGKS201 in a group with a pseudoconversation LUname relation, routed as described in the following text.

In this example, each instance of transid AAAA from a terminal starts a pseudoconversational-lifetime affinity. AAAA can be routed to any suitable target region (AOR1 through AOR6), but other transactions in the group, in the same pseudoconversation with the same terminal (IGKS201 in this example), must be routed to whichever target region is selected for AAAA.