MPE/iX 5.5 Operating System Limits

VSOD table, kso #255). All non file transient objects obtain an entry in the VSOD table
when they are mapped in (or created). When the object is mapped out, the entry is
released. There is no LRU list for the VSOD, as there is for the the VSOD GUFD.
This table limits the number of transient objects to 399457. Each entry in the VSOD
table, representing a non-resident object, will have a pointer to one node in the Extent B-
tree or Extent AR B-tree table. As discussed in the Extent B-tree documentation, one or
more nodes of the B-tree may be used for any given object, depending on the number of
extents that have been allocated for it.
(8) VS b-tree table - KSO047
Every object in the system requires an entry in VS B-tree. Each entry (or node) of this b-
tree can describe up to 32 different objects. Each object described by this b-tree will have
a corresponding entry in the VSOD, VSOD GUFD, or Disabled Expandable VSOD table.
When the object is mapped out, the entry is released.
This table contains 30840 entries, therefore, if it was completely full, it would limit the
total number of open objects on a system to 986880. This limit is obtained by multiplying
the the number of entries (30840) by the maximum number of entries per node (32).
(9) VS domain desc table - KSO061
VS domain descriptor table contains one entry per process or job on the system. Entries
are "added" when a new virtual space domain is needed, such as when a job or process is
created. Theoricaly, this table will never contain more entries that MAX number of
process on system (5460) + Max number of job or session on system (1700) + 1 (system
domain) = 7161 entries.
Transaction management:
Item Limit Description Resource Table
1 10 XM Control Block Locks per Transaction XM Locks
2 4096 Open Files during Recovery Open Files During Recovery
3 4096 Open Transactions during Recovery Open Transaction During