Naming dynamically defined dependent LUs

When a dependent LU is being dynamically defined for the first time on a PU, the SDDLU exit must create a unique name for the LU. VTAM® supplies the exit with fields of information to use to generate the LU name.

The IBM® default exit uses the LUSEED operand on the PU's definition statement and the LU's local address to generate the name. See z/OS Communications Server: SNA Network Implementation Guide for a description of the algorithm used to create the LU name.

A user-written exit can use its own method to create the LU's name. VTAM supplies the exit with the following information that the exit can use to create the name:

LUSEED operand (if coded)
PU name
Line name
Local address
LU encryption key name
Major node name of the line
Network ID
Subarea number
SSCP name
Address of Reply/product-set identification (PSID) major vector sent to VTAM

If an LU was previously defined through the dynamic definition function, VTAM passes the current name of the LU to the exit, but the exit cannot change the name.