Use the LPA statement to specify:
- Modules that are to be added to the LPA at the end
of the IPL. This is needed only for program objects within PDSEs but
can be used for load modules within PDSs.
- Modules that are to be added to the LPA following IPL.
- Modules that are to be deleted from the LPA following IPL.
- Threshold values for minimum amounts of
CSA storage that must be available after an ADD operation.
You can also initiate a change to LPA from a program via the CSVDYLPA
macro, or by an operator using the SETPROG command. The PROG system
parameter can be used to specify CSA threshold values, but not to
request ADD or DELETE operations.
You can exercise certain controls over the modules to be loaded:
- You specify a data set from which the system is to load the modules.
You must be authorized to make the request.
- You can request that the modules be placed into fixed common storage.
- You can request that only the full pages within a load module
be page-protected. This does leave the likelihood of the beginning
and/or end of a load module not being page protected. By default,
each module is individually page-protected. This is, however, wasteful
of common storage, as each module needs then to occupy a whole number
of 4096-byte pages. In all cases the module will be in key 0 storage.
- You can indicate that the module being replaced
is the routine for a specific SVC. In this case, the system updates
the SVC table for the specified SVC with the new entry point address.
By default, LPA module alias names are not automatically
handled. By default, if a module has aliases, the module name
and all associated aliases must be specified within the same request.
Otherwise, one of the following outcomes could occur, depending upon
the initial state of the system:
- The module name or alias will not be found
- A duplicate copy of the same module will be loaded
- A previous copy of the module will be used.
You can use the ADDALIAS option to indicate that
the system is to process aliases of the specified modules.
LPA modules are considered as coming from an authorized library.
As part of its LPA search, the system finds modules that were added
dynamically. A module added dynamically is found before one of
the same name added during IPL.
The LPA statement is intended to replace modules only in cases
where the owning product verifies the replacement. Otherwise, replacement
could result in partial updates, or if the module address has already
been saved by its owning product, an LPA search will not be done and
the updated module will not be found.
It is sometimes necessary to re-IPL to replace LPA modules. For
example, many service updates of LPA modules will require a re-IPL.