Another feature of Specific LU name requests is that the client can specify an LUGROUP name, and Telnet will assign an available LU from that pool. This capability is useful when different applications require different LU naming schemes, but each user client does not need to use an exact LU name for each emulator. For example, an administrator can create three pools, one for each of three applications. Only three client emulators need to be set up. One for TSO which requests LU name LUTSO, one for CICS® which requests LUCICS, and one for IMS™ which requests LUIMS. Assume the general users are in subnet 3.0.0.0. Any client connecting with a Client Identifier of IPGGEN can be set up to issue a Specific request for LU pool LUTSO, LUCICS, or LUIMS, and will be assigned an LU from the appropriate pool.
After an LU is assigned, the DEFAPPL option will cause Telnet to immediately issue a session request for the appropriate application. If LOGAPPL is coded and the application is not active, VTAM® will continue session initiation after the application is active.
In most cases, DEFAPPL on multiple Generic LUMAPs is not useful. LUs are assigned in order starting with the first LUMAP statement. One case that may be useful is if an application has a user limit but can be cloned. Assume the INVENTRY application can support only 20 users but can be cloned. Multiple LUMAPs with DEFAPPL will direct the first 20 HNGINV clients to INVENTRY, the next 20 HNGINV clients to INVENTR2, and the next 20 HNGINV clients to INVENTR3.
IPGROUP IPGGEN
255.0.0.0:3.0.0.0
ENDIPGROUP
LUGROUP LUTSO TSO00001..TSO00999 ENDLUGROUP
LUGROUP LUCICS CICS0001..CICS0999 ENDLUGROUP
LUGROUP LUIMS IMS00001..IMS00999 ENDLUGROUP
HNGROUP HNGINV
*.INVDEPT.COM
ENDHNGROUP
LUGROUP LUGINV1 LUINV01..LUINV20 ENDLUGROUP
LUGROUP LUGINV2 LUINV21..LUINV40 ENDLUGROUP
LUGROUP LUGINV3 LUINV41..LUINV60 ENDLUGROUP
LUMAP LUTSO IPGGEN SPECIFIC DEFAPPL TSO LOGAPPL FIRSTONLY
LUMAP LUCICS IPGGEN SPECIFIC DEFAPPL CICS LOGAPPL
LUMAP LUIMS IPGGEN SPECIFIC DEFAPPL IMS LOGAPPL
LUMAP LUGINV1 HNGINV DEFAPPL INVENTRY LOGAPPL DEFONLY
LUMAP LUGINV2 HNGINV DEFAPPL INVENTR2 LOGAPPL DEFONLY
LUMAP LUGINV3 HNGINV DEFAPPL INVENTR3 LOGAPPL DEFONLY Pool name specification is a powerful mapping method because multiple LUMAP statements with different Objects can be used for a single Client Identifier.