Update SYSIBM.LUMODES with conversation limits

Use SYSIBM.LUMODES to provide VTAM® with conversation limits for specific LU name and mode name combinations.

About this task

Begin general-use programming interface information.

Populating SYSIBM.LUMODES is optional; if you do not specify mode names in this table, the VTAM defaults are used. The table is unlike the DSESLIM option of the VTAM APPL definition statement, which provides the default session limits for all LU name and mode name combinations. The primary key for this table is formed by the LU name and mode name combination. Only one entry with the same LU name and mode name is allowed.

LUMODES is accessed for negotiation of session limits with a remote Db2 for a specific mode. This negotiation is called change number of sessions (CNOS).

Example

For example, suppose Spiffy wants to allocate 75 sessions instead of 50 (the value in DSESLIM) for conversations to USIBMSTODB22, using the mode named LOC2MODE. They can use the INSERT statement below to update the value in the CONVLIMIT column to 75. The new session limit takes effect the next time DDF is started, or in the initial connection to this LU for this mode.

INSERT INTO SYSIBM.LUMODES VALUES ('LUDB22','LOC2MODE',75,'N');

Start of change CNOS processing negotiates a value that is the lesser of the number of sessions available at either system for that mode. Therefore, USIBMSTODB22 must also increase its CONVLIMIT value to at least 75. End of change

Start of change See CNOS processing in Db2 for an example of how CNOS processing works. End of change

Columns of the LUMODES table:

LUNAME CHAR(8): Again, this is the LU name of the other system. This column is a foreign key of the LUNAMES table; thus, all LU names defined in this table must be defined in LUNAMES. When you delete an LU name from the LUNAMES table, all associated rows in LUMODES are deleted.
MODENAME CHAR(8): The name of the logon mode description in the VTAM logon mode table that VTAM uses when creating a conversation to support the request from the local Db2 for data from another system. The mode named here must exist in the mode table used by Db2 before a conversation can be created between USIBMSTODB21 and USIBMSTODB22.
CONVLIMIT SMALLINT: The maximum number of conversations to be concurrently active between this Db2 subsystem and the other system for this mode. This number overrides the number in the DSESLIM option of the VTAM APPL definition statement during CNOS processing..

End general-use programming interface information.