Guardian Programmer's Guide

Table Of Contents
Glossary
Guardian Programmer’s Guide 421922-014
Glossary - 26
run unit control block (RUCB)
run unit control block (RUCB). A data structure used by the INITIALIZER procedure to
specify to SIO the name of the common FCB and the number other SIO FCBs to be
created.
secondary extent. A contiguous area of disk storage allocated to a file. A file is made up of
one or more extents; the first extent is the primary extent, and other extents are
secondary extents. The secondary extents are all the same size for a specific file. The
primary extent can be a different size. See also primary extent.”
segment. In general, a contiguous sequence of logically related pages of virtual memory.
The pages of the segment are individually swapped in and out of physical memory as
needed. Within a loadable object file, one of the portions of the file that is mapped as
one unit into virtual memory as the file is loaded. See also code segment and data
segment.
segment ID. A number that identifies an extended data segment and specifies the kind of
extended data segment to allocate.
selectable segment. A type of logical segment formerly known as an extended data
segment. The data area for a selectable segment always begins with relative segment
4, and this area can be dynamically switched among several selectable segments by
calls to the Guardian SEGMENT_USE_ procedure. The effect is similar to a rapid
overlaying of one large data area. See also logical segment and flat segment.
sequence number. See process sequence number.
server. (1) An implementation of a system used as a stand-alone system or as a node in an
Expand network. (2) A combination of hardware and software designed to provide
services in response to requests received from clients across a network. For example,
HP NonStop™ servers provide transaction processing, database access, and other
services. (3) A process or program that provides services to a client or a requester.
Servers are designed to receive request messages from clients or requesters; perform
the desired operations, such as database inquiries or updates, security verifications,
numerical calculations, or data routing to other computer systems; and return reply
messages to the clients or requesters. A server process is a running instance of a
server program.
shared data segment. An extended data segment that can be accessed by more than one
process.
shared memory. An interprocess communication mechanism that allows two or more
processes to share a given region of memory.
Shared Millicode Library. An intrinsic library containing privileged or TNS-derived millicode
routines used by many native-compiled programs and by emulated TNS programs.
This library includes efficient string-move operations, TNS floating-point emulation, and
various privileged-only operations. These routines are mode independent. They
comply with native calling conventions but can be directly invoked from any mode
without changing execution modes.