Specifying a model LU

In addition to naming the dynamically defined LUs, the SDDLU exit can also indicate which model LU from the PU's model LU group VTAM® is to use when creating the LU's definition.

VTAM supplies the exit with the 7-character EBCDIC machine type and model number (the product set ID) of the device that powered on. The IBM® default exit uses the machine type and model number as the name of the model LU that VTAM uses to create the LU's definition.

A user-written exit can use the product set ID (PSID) supplied by VTAM for the model LU name, or it can derive any other value for the model LU name. Because VTAM provides the SDDLU exit with the address of the Reply/PSID major vector, a user-written exit can use other device-specific subvectors that might be present in the major vector to select a model LU name. For example, subvectors X'04' (SNA Address List), X'10' (Product Set ID), and X'82' (Port-Attached Device Configuration Description) are present in the major vector passed to the exit. In addition, depending on the product, subvector X'88' (Detailed Data) might be present in the major vector. For additional information, see the following publications:

Product publications for the PU type 2.0 or 2.1 devices that support Reply/PSID NMVTs for dynamic definition of dependent LUs contain detailed information about the other subvectors present in the major vector.
See SNA Formats for detailed information about the Reply/PSID NMVT and its subvectors.
z/OS Communications Server: SNA Network Implementation Guide contains an example of how VTAM builds dynamic definitions for dependent LUs.