ZCOM Tables and Data Structures

ZLU Tables

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 entry 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 that 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

 

 

 

 

Chapter 3

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