gtpi1m5uSystem Installation Support Reference

Terminology

The following glossary of selected terms gives a quick overview of terms used throughout this chapter; it is not intended to be complete and exhaustive. Rather than being listed alphabetically, the terms progress from simple to more complex concepts.

globals.
A generic term referring to any or all of the entities in the area of main storage called the global area or to copies of these entities on DASD.

global record.
A logical collection of data, treated as a single entity, that can reside in the main storage global area and that also resides on DASD as large (1055-byte) records (also called application core-resident records). As that name implies, global records are typically used by application programs that need convenient access to main storage records. TPF macros provide a variety of efficient services for retrieving, addressing, and filing these records. The records can have various attributes such as keypointability, SSU uniqueness or commonality, and I-stream uniqueness or commonality.

global field.
A subset of certain global records, ranging in size from 1 to 256 bytes in length. Global fields are individually addressable using the GLOBZ macro, and they can share many of the attributes of global records.

global block.
The global records loaded from DASD with an ID of GL. These records contain the data that make up the global fields, and they are the first items loaded into global areas 1 and 3.

global directory.
A series of 8-byte fields at the start of global area 1 and global area 3 that point to the main storage address and file address of global records. These pointers are defined, respectively, by the GL0BA and GL0BY DSECTs.

subsystem user (SSU) unique/common.
In a system with the Multiple Database function (MDBF), global records and fields can be shared among subsystem users (SSUs) in a subsystem or can be unique for each SSU. In other words, an ordinal number used by different SSUs either points to the same common record or to different unique ones.

I-stream unique/shared.
Records in a tightly coupled (TC) system can be declared unique or shared among I-streams. This term applies only to global records (not global fields) and only to main storage copies (not DASD copies).

primary globals.
Globals that reside below the 16MB boundary and are therefore accessible to programs running in 24-bit addressing mode.

extended globals.
Global records that reside in an area of storage defined above the 16MB boundary. The extended global area greatly expands the amount of storage available for globals and relieves constraints on the amount of storage available for data that must be accessible to programs running in 24-bit addressing mode. For each primary global area there is a corresponding extended area. A system can be generated with or without extended globals.

global attribute table (GAT).
Each global directory slot has a corresponding global attribute table entry that identifies the characteristics of the global for example, SSU unique/common or I-stream unique/shared. System programs use a special macro to address this table; application programs do not require access to it.

SSU table.
A table generated during system restart that contains, for each SSU in the system, the address, size, and protection key of each associated primary and extended global area and GAT. The SSU table is organized by I-stream within global area within SSU. (The global area organization is SSU within I-stream within global area).

global storage allocator (GOA).
A #GLOBL fixed-file record that contains the information needed by the Application Core Load program (GOGO) to load all the other #GLOBL records to the global areas (see data macro GO1GO). A GOA must be manually prepared for each SSU as input to the System Test Compiler (STC) so that it becomes part of a pilot tape. The first such record in a chain is called the prime GOA.

super GOA.
#GLOBL fixed file records that are used by the GOGO program as an index to find the GOA associated with each I-stream/SSU combination. A super GOA must be manually prepared as input to system test compiler (STC) so that it becomes part of a pilot tape.

global synchronization.
A process that permits changes made to global fields and records to be communicated among 2 or more active I-streams in a loosely coupled (LC) or tightly coupled (TC) system to maintain currency. Synchronization involves offline data record generation, online restart processing, and real-time application interface processing.

system interprocessor global table (SIGT).
In an LC or TC system, a table that stores information necessary for controlling the locking, unlocking, and synchronization of user-specified synchronizable global records or fields.