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Coupling Facility LP Storage Planning Considerations
You must define at least 128 MB of central storage for a coupling facility LP to
activate.
This storage is reserved for coupling facility control code use and cannot be used
for other purposes. Minimum storage size for coupling facilities is primarily a
function of the coupling facility control code level. This implies that, over time, the
minimum storage size required by a coupling facility on a particular machine can
grow as new coupling facility control code updates are applied.
You must also define additional storage to accommodate the shared structures and
dump space used by software subsystems using the coupling facility.
If a hot standby back-up coupling facility is defined, you must allocate to the
back-up coupling facility all the storage required by that coupling facility to handle
the structures it may need to hold in an active take-over role. Storage resources for
coupling facility LPs are static and must be allocated at LP activation time of the
coupling facility LP. This includes coupling facility LPs using ICF or dynamic
coupling facility dispatching, or dynamic ICF expansion.
Structures, Dump Space, and Coupling Facility LP Storage
A coupling facility allocates storage for structures and for dump space based on
values specified in the SIZE, INITSIZE, and DUMPSPACE parameters of the
coupling facility resource management (CFRM) policy used for the coupling facility.
Structures consist of control objects and data elements. The control objects include
entries and a variety of other control structures used to manipulate the entries. The
data elements store user data associated with structure entries.
Dump space is storage in the coupling facility set aside for use as a dump table
when a structure dump is taken. Dump tables are used for application development
and problem determination purposes.
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Chapter 2. Planning Considerations
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