HP-UX SNAplus2 Upgrade Guide (June 2003)

Changes in SNAplus2 Functions in R6.0 and later releases
APPC and CPI-C Applications Using Default LUs
Chapter 4 69
APPC and CPI-C Applications Using Default
LUs
Instead of specifying a local LU name explicitly, an application can
request to use a default local LU (by specifying a blank LU name on the
APPC TP_STARTED verb, or by not setting the APPCLLU environment
variable for a CPI-C application). In SNAplus, the LU was not selected
until the application issued the Allocate, so the application could issue
multiple Allocates for the same TP and get a different LU from the
default pool for each one.
In Release 6, the default LU is selected when the APPC application
issues TP_STARTED, or when the CPI-C application issues its first
Allocate call; all conversations from this TP use the same local LU. For
dependent LUs, which cannot support parallel sessions, this means that
the application cannot have multiple concurrent conversations in one TP
(from one TP_STARTED verb) because the LU only supports one
conversation at a time.
For an APPC application, you can support multiple concurrent
conversations by redesigning the application so that it issues a separate
TP_STARTED verb for each conversation. Each of these verbs is then
assigned to a different local LU in the pool.
In addition, if you are defining partner LUs that can be accessed using
default LUs, partner LU definitions in Release 6 are specific to a node
and are not defined globally for all nodes in the SNAplus2 domain. If you
are defining default LUs on more than one node, you need to ensure that
the partner LUs are defined on all of these nodes, so that the appropriate
partner LU can be accessed from any of the default LUs.