Information passed to the dynamic routing program

The CICS® relay program, DFHAPRT, passes information to the dynamic routing program by using a communications area. The communications area contains fields that are mapped by the DSECT DFHDYPDS.

The DFHDYPDS DSECT is described in detail in Parameters passed to the dynamic routing program. For transaction routing, here is the data that is passed to the dynamic routing program in the communications area:
  • The SYSID of the remote CICS region that was specified when the transaction was installed
  • The netname of the remote CICS region
  • The name of the remote transaction
  • The priority of the relay transaction task, for MRO and IPIC connections only
  • Whether the request is to be queued if no sessions are immediately available to the remote CICS region
  • The address of the communications area of the remote transaction
  • The address of a copy of the terminal input/output area (TIOA)of the transaction
  • A task-local user data area.
  • Application context data.

The communications area DSECT contains comments to describe the information that is passed.

The dynamic routing program can accept these values, or change them, or tell CICS not to continue routing the transaction. The values that are used depend on the function that is being performed; that is, some values might be ignored.

The information that is passed to the dynamic routing program indicates whether the transaction is being routed dynamically or statically. If the transaction is being routed dynamically, the dynamic routing program can change the SYSID or netname to determine where the transaction is to run.

Sometimes, the dynamic routing program is invoked for transactions that are routed statically. It is invoked if a transaction defined as DYNAMIC(YES) is initiated by automatic transaction initiation (ATI), for example, by the expiry of an interval control start request, but the transaction is ineligible for dynamic routing. In this case, the dynamic routing program is called only to notify itself of where the transaction is going to run. It cannot change the remote system name, and any changes it makes to the SYSID or NETNAME fields in the communications area are ignored.

For transactions that are run remotely, either because they are defined as remote or because they are dynamically routed to a remote CICS region, CICS monitoring is informed of the SYSID of the remote CICS region. For transactions that the dynamic routing program routes locally, the monitoring field is set to nulls.