ACC Programmer's Reference Guide

Chapter 3 57

ZCOM Tables and Data Structures

ZLU Tables

The ZCOM logical unit table relates a terminal device or a program

queue with a number or logical unit. The ZCOM logical units are called

ZLUs to distinguish them from the HP-UX logical units (LUs).

Each ZLU e ntry structure contains 40 bytes of data.

The ZLU table is split into two logically distinct parts. The first part is

the physical terminal area, and the second the dynamically assignable

program ZLUs. The latter are used for program input queues. The ZLUs

can be mapped so t hat a particular ZLU can point to any other ZLU.

Individual ZLU Entries

The individual ZLU data structure (zlu_type) layout is shown in Table

3-7.

Table 3-7 Individual ZLU Data Structure (zlu_type)

Field Name Field Description Field Type Size

(Bytes)

zcksum ZLU checksum uns.short 2

zlttype ZLU type uns.short 2

zpoint ZLU pointer or mapped node nmbr uns.short 2

zmpzlu Mapped ZLU number uns.short 2

zmpzcs Mapped ZLU checksum uns.short 2

zlname ZLU Name (8 bytes) char [8] 8

zowner PID number of owner uns.short 2

ztimer Timeout interval (seconds) short 2

zclock Timeout clock short 2

zlock ZLU lock pointer pointer 8

refcnt Lock reference count unns.int 4

spare1 Reserved, not used int 4