MPE/iX 5.5 Operating System Limits

The Code Segment Table (CST) is used to manage Compatibility Mode (CM) code
segments which are a part of a Segmented Library (SL). There are 255 entries reserved
for physically mapped segments. Physically mapped segments are reserved for use by the
system. These typically reside in SL.PUB.SYS. The remaining entries are available for
user library segments. These are referred to as logically mapped segments.
A CST entry is allocated whenever an SL segment is loaded for the first time. This occurs
when:
- A CM program is executed via the :RUN command with the ;LIB= option.
- SL segments are :ALLOCATEd.
- A procedure (in an SL) is loaded via the LOADPROC intrinsic.
CST entries are shared. Loading an SL segment after the first time will not result in the
allocation of a CST entry. Share counts on segments are maintained in the Loader
Segment Table (LST). The share count for a segment is decremented when the segment is
unloaded. When the share count for a particular segment drops to zero, the CST entry for
that segment is released.
The CST table limits the number of compatibility mode library segments.
(2) Code segment table ext
The Code Segment Table Extension (CSTX) is used to manage Compatibility Mode
(CM) code segments which are a part of a CM program. There is one CSTX for each CM
program that is loaded or :ALLOCATEd. Each CM program can reference up to 255
logically mapped segments. Logically mapped segments include those that are a part of
the program file and any user SL segments that are referenced. Each logically mapped
segment that is a part of the program file will use an entry in the processes' CSTX.
Logically mapped user SL segments will count toward the maximum number of 255
logically mapped segments, but will use CST entries instead of CSTX entries.
This table limits the number of logically mapped compatibility mode segments in any
program file to 255.
(3) Data segment table - KSO192
The Data Segment Table (DST Table) is used to manage Compatibility Mode (CM) Data
Segments (DSTs). There is a maximum of 16383 entries in the DST Table.
Several DSTs are used by the Operating System (and other system software, eg: Data
Communications software) for global system data structures. It is difficult to estimate