Page of SY20-0884-3 As Updated Aug. 1, 1979 by SN25-0497 This publication contains descriptions of
major data areas and control blocks used by
the three major compoQents of VM/370. The
three components are: The control Program (CP) The Conversational Monitor System (CMS) The Remote Spooling
Subsystem (RSCS) Communications
There are three sections
appendixes, as follows:
and five "Section 1. CP Data Areas and Control
Blocks" contains information about CP data areas and control blocks. "Section 2. CMS Data "Areas and Control
Blocks" contains information on CMS data
areas and control blocks. "Section 3. RSCS Data Areas and Control
Blocks" contains information on RSCS data areas and control blocks. "Appendix A. CP and RSCS Equate Symbols"
contains assembler language equate
symbols used by CP and RSCS to reference
data. "Appendix B. RSCS Control Areas"
contains RSCS control areas that define
constants and variables used during
execution .. "Appendix C. RSCS Request Elements"
contains RSCS request elements that are
the tables used by RSCS for task-to-task
communication. "Appendix D. CMS Equate
contains CMS equate symbols. Symbols" "Appendix E. Data Areas and Control
Block References" contains information
on the modules that reference data areas
and control blocks. OTHER VM/370 DATA AREAS AND CONTROL BLOCKS Some data areas and control blocks that
affect VM/370 service and support programs
are not included in this publication.
Information on these data areas and control
blocks can be found in the RELATED PUBLICATIONS This publication
conjunction with:
should be
used in Logi£ Qetermi.!@tiQB Gu!de, !olumg 1 Order No. SY20-0886 QYiQg, Order No. GC20-1807 For information on how to use the fourth
component interactive problem control
system --and its facilities, the hardware
and software support personnel or the
installation system programmer should use:
This publication addresses and describes
the major control blocks associated with CP, CMS, and RSCS. Generally, data areas,
or scratch areas that are created and exist
only during the execution of a particular
module are not described in this
publication. In this publication, the data and control blocks are arranged in
alphabetical order by DSECT name.
The CMS and RSCS components operate
under control of CPo Each component
creates, updates, and erases its own
control blocks and data areas. Preface iii
Page of sY20-0884-3 As Updated Aug. 1, 1979 by sN25-0497
Control blocks and data areas are blocks
of related information applicable to one or
more system functions. They are usually
defined by the DsECT instruction. The
blocks can reflect current status, history
information, or combinations of both,
applicable to V8/370 functions. Control
blocks and data areas provide the linkage
and information for the user, the hardware,
and the programs to work as one entity for
the successful execution of a job, task, or
For every data area or control block, a
statement is given that defines the use of
the data area or control block. This
statement is followed by a formatted block
showing the fields defined in the data area
or control block and the displacement into
the DsECT of that field.
The formatted blocks for CP and CMs control areas are 8 bytes wide, showing two
fullwords per line. RsCs control blocks
are 4 bytes wide. One exception to this width rule is
the formatting for PsA, where the control
areas are given in 16-byte width. When the name of a field is too large to
fit into the formatted line, a pointer to
the definition of the field is used instead
of the name of the field. This pointer
usually takes the form A*1, A*2. etc. When there is a particularly large field (one
that uses more than three or four lines of
the formatted block), ellipses are used in
the block to show that the displacement of
this field is larger than can be shown in
the block.
The use of slashes in a field indicates
that the field is reserved for IBM's use.
The formatted block is
listing-related information
hexadecimal displacement of
the DsECT, the name of the
definition in the listing,
description of the contents
the field.
followed by
such as the
the field into
field and its
and a brief
and meaning of
The following terms in this publication,
refer to the indicated support devices: "2305" refers to IBM 2305 Fixed Head
storage, Models 1 and 2. "270x" refers to
2703 Transmission IBM 2701, 2702, and
Control Units or the Integrated Communications Adapter (lCA) on the system/370 Model 135. "2741" refers to the IBM 2741 and the
3767, unless otherwise specified. "3270" refers to a series of display
devices, namely, the IBM 3275, 3276,
3277, and 3278 Display Stations. A
specific device type is used only when a
distinction is required between device
Information about display terminal usage
also applies to the IBM 3138, 3148, and
3158 Display Consoles when used in
display mode, unless otherwise noted.
Any information pertaining to the IBM 3284 or 3286 Printer also pertains to
the IBM 3287, 3288, and 3289 printers,
unless otherwise noted. "3330" refers to the IBM 3330 Disk
storage, Models 1, 2, or 11; the IBM 3333 Disk Storage and Control, Models 1
or 11; and the 3350 Direct Access
Storage operating in 3330/3333 Model 1
or 3330/3333 Model 11 compatibility
mode. "3340" refers to the IBM 3340 Disk
storage, Models A2, B1, and B2, and the 3344 Direct Access Storage Model B2. "3350" refers to the IBM 3350 Direct
Access Storage Models A2 and B2 in
native mode.
"370x" refers to IBM 3704 and 3705
Communications Controllers.
The term "3705" refers to the 3705 I and
the 3705 II unless otherwise noted.
iv IBM VM/370 Data Areas and Control Blocks Logic
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