MPE/iX 5.5 Operating System Limits

(1) Extent b-tree table - KSO055
Each entry in the Extent B-tree is a node, which can describe up to eight extents. If an
object contains more than eight extents, it will use additional entries (or nodes). Every
non-resident object (with fixed access rights), will obtain one or more entries in the
extent b-tree when it is mapped in (ie. opened). See the NOTE: below for a description of
access rights.
This table limits the maximum number of open non-resident objects with fixed access
rights to 246723. The total number may be less if one or more objects require more than
one entry (or node) due to the fact that they have more than eight extents.
This table also limits the maximum number of extents for open non-resident objects with
fixed access rights to 1973784. It is unlikely that this maximum number could be
obtained since it would imply that each object has a multiple of eight extents and the tree
is completely balanced and full. This number was obtained by multiplying the maximum
number of entries (246723) by the maximum number of extents per entry (8).
NOTE: Objects with fixed access rights are defined as those for which ALL pages have
identical read and/or write access as well as the same privilege level. Extent information
about objects with fixed access rights is kept in the Extent B-tree (KSO 55). All but two
types of objects have fixed access rights. However, NM program files and NM library
files have variable access rights. Page 0 has write access in addition to the read/execute
access that is given to the other pages of the file. Extent information about objects with
variable access rights is kept in the Extent AR B-Tree (KSO 57).
(2) Extent ar b-tree table - KSO057
Each entry in the Extent AR b-tree is a node, which can describe up to 8 extents. If an
object contains more than eight extents, it will use additional entries (or nodes). Every
non-resident object (with variable access rights), will obtain one or more entries in the
Extent AR B-tree when it is mapped in (ie. opened). See the NOTE: below which
describes access rights.
This table limits the maximum number of open non-resident objects with variable access
rights to 8065. The total number may be less if one or more objects require more than one
entry (or node) due to the fact that they have more than eight extents. Since there are only