DB2 Server for VM: System Administration

Operating VSE Guest Sharing

Your VSE online users can access an application server on a VM host operating system when the VSE operating system is running as a guest in a virtual machine. Database switching is supported for CICS online applications, which means that one resource adapter in one CICS region can connect to multiple application servers. Any CICS transaction in the CICS region can connect to any of the DB2 Server for VM application servers to which the online resource adapter has established connections. This means that:

1. Different transactions in a CICS region will be able to connect to different DB2 Server for VM application servers
2. Single transactions will be able to connect to different DB2 Server for VM application servers in different units of work.

The DB2 Server for VM application server can be accessed by specifying the server_name parameter on the CIRB transaction or on the CIRA transaction. The DB2 Server for VM application server must be defined in the DBNAME Directory. The DBNAME Directory provides the mapping of mapped DBNAME to resid. See for more DBNAME Directory information. The resid is the basic DBNAME, and must be the same as the one specified in the SET APPCVM command during the VSE initial program load. If there are multiple DB2 Server for VM servers on the VM host, there can be more than one SET APPCVM command.

The VM application server being accessed can be either on the same processor or on another processor in the network. For batch applications and for online users who want to access an application server on another processor in a SNA network, you must issue the SET APPCVM command when you start VSE. The command provides routing information for both batch and online users. Note that SET APPCVM is required only if VTAM is to be used in the connection. If the server and requester are in a TSAF collection on the same node, it is not necessary to issue the SET APPCVM command.

Figure 19 shows the syntax of the SET APPCVM command.

Figure 19. SET APPCVM Command

>>-SET APPCVM TARGET----+-resid------------------------+------->< '-+-------------------------+--' '-| avs_parameter_block |-' avs_parameter_block |--(--resid,gateway_name,target_LU_name,mode_name--)------------|

The variables have the following meanings:

resid

The resource identifier of the DB2 Server for VM application server which is the same as the resid parameter on the IUCV *IDENT entry in the database machine directory for VM operating systems.

avs_parameter_block

Only specify these parameters if the application server you want to access is in an SNA network. The names are defined by VTAM statements when the network is built, and have these meanings:

resid

The resource identifier of the DB2 Server for VM application server. This is the same as the resid parameter on the IUCV *IDENT entry in the database machine directory on VM.

gateway_name

This corresponds to an APPL statement at the local system. To the SNA network, gateway_name is an LU with the same name.

target_LU_name

This corresponds to an APPL statement at the remote system.

mode_name

This corresponds to a mode table entry at the local and remote systems.

The parameters must be specified in the order shown above.

For more information about the AVS parameters, see the VM/ESA: Connectivity Planning, Administration, and Operation manual. For more information on the IPL SET APPCVM command in VSE, see VSE/ESA System Control Statements.

Note:

The VSE Guest sharing facility requires 40KB of real storage for each database communication link. For more information on providing real storage, see VSE/ESA System Control Statements