Abbreviations and glossary

This chapter provides an alphabetical list, accompanied by explanations, of the abbreviations and technical terms used in this manual.

ADM-PFA caching	Administrator-controlled Performant File Access caching.
Cache ID	Identifier of a cache area.  The identifier of an cache area is defined either by systems support via the CACHE-ID operand of the START-DAB-CACHING command, or assigned internally by DAB if systems support does not define a cache ID.
DAB	Disk Access Buffer
DMS	Data Management System
DRV	Dual Recording by Volume
DSSM	Dynamic Subsystem Management
FIFO	First In - First Out - Strategy for handling a queue.
HIPLEX	Highly Integrated System Complex
I/O	Input/Output
LMS	Library Maintenance System
LRU	Least Recently Used Selection and replacement strategy. When new data is stored, the blocks selected for replacement are those which have been least recently used.
Locality	A good locality of the data ensures a high hit rate for caching according to the LRU principle. A distinction is made between “temporal locality” and “spatial locality”. “Temporal locality” implies that more often than not, the data referenced and therefore cached last will be accessed again. “Spatial locality”, on the other hand, implies that more often than not, the data spatially adjacent to the referenced data will be accessed next. This requires the prefetching mechanism to be enabled in order to increase the probability that the cache already contains the spatially adjacent data accessed next.
MM	Main Memory (cache medium)
MSCF	Multiple System Control Facility
NDM	Nucleus Device Management (Device management in BS2000)
Operator Console	Workplace at which the operator carries out his or her tasks.
Pubset	Public volume set (PVS): Common set of disks available to all users.
PVS ID	Identifier of a pubset. In path names, it is specified in the form :catid:
SDF	System Dialog Facility
SF pubset	Single-Feature pubset
SM pubset	System-Managed pubset
SRV	Single Recording by Volume; A data management method which stores only one copy of the data on a physical disk (see “DRV”).
SVL	Standard Volume Label - Includes the VSN.
VSN	Volume Serial Number
XCS network	Cross Coupled System