Transcript No Slide Title

Introduction To IBM
Mainframe Systems
Chapter 1-2 Review
Stephen Linkin
Houston Community College
January 15, 2007
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
1
Objectives


Identify Basic Components Of Mainframe Processors
Identify Difference In Architecture

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Types Of I/O Devices On Mainframes
Define Tracks And Cylinder
Describe Features Of Mainframe OS:
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IBM’s z/Series Processors And Earlier Systems
Virtual Storage
Multiprogramming
Spooling
Batch Processing
Time Sharing.
Describe MVS, OS/390, And Z/Os
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
2
The Basic Architecture For IBM
Mainframe Systems

Process
or
The z/OS Redbook Shows How It Evolved Into--Channel 0
Channel 1
Channel 2
Channel 3
CPU
Main
Storage
I/O
devices
Channel 4
Channel 6
Channel 7
Channel 8
Figure 1-01a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
3
Hardware Terms You Should
Know

Central processing unit, or CPU
 Cache
 Channels (ESCON/FICON channels)
 I/O devices
 Multiprocessor systems
 PR/SM
 Logical partitions (LPAR’s)
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
4
I/O Devices That Connect To
Mainframe Servers

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Direct access storage devices, or DASD
Tape Drives and Optical Disks
Display And Other Terminals
Printers
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
5
Virtual Storage
An overview of virtual storage and multiprogramming
Mainframe system
Virtual storage
Pro g ra m A
R e a l sto ra g e
(m a i n
sto ra g e )
CPU
Pro g ra m B
D i sk
sto ra g e
Pro g ra m C
Figure 1-08a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
6
Spooling
How the operating system spools output from
application programs
Mainframe system
P r ogr a m A
“ p r i n te d ” o u tp u t
Fi l e fo r p r o g r a m
A o u tp u t
P r ogr a m B
“ p r i n te d ” o u tp u t
Fi l e fo r p r o g r a m
B o u tp u t
P r ogr a m C
“ p r i n te d ” o u tp u t
Fi l e fo r p r o g r a m
C o u tp u t
Ou tp u t
to p r i n te r
P r i n te d o u tp u t
Spooling disk
Figure 1-09a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
7
Batch Processing
How batch processing works
J OB 1 :
Program A
Program B
J OB 2 :
Program A
Program B
Program C
Mainframe system
J ob
s c he dule r
J OB 1
J OB 3
J OB 2 :
Program A
Program B
Program C
CPU
J OB 3 :
Program A
Figure 1-10a

Job Control Language
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
8
Time Sharing
Multiple users in a time sharing environment
Mainframe system
Running
o r d e r e n tr y
program
Running
o r d e r e n tr y
program
C r e a ti n g
J C L fo r
b a tc h j o b
Developing
a p p l i c a ti o n
program
User 1
User 2
User 3
User 4
Figure 1-11a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
9
Time Line
The evolution of the OS/390 and z/OS operating system
OS
(Operating
System)
for S/360
1960's
1964
O S / V S1
O S / V S2
(S V S )
1974
1 9 7 0 's
OS/MFT
O S /M V T
M V S /E S A
version 5
M V S/X A
1988
1983
1995
1994
M V S/ E S A
version 1
M V S /3 7 0
z/0S
2001
O S/ 3 9 0
Figure 1-12a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
10
A Partial Listing Of OS/390 And
z/OS Services

Base Control Program (BCP or MVS)
 Workload Manager (WLM)
 Systems Management Services
 Application Enablement Services
 OS/390 UNIX System Services
 Distributed computing services
 Communication Server
 LAN Services Network Computing Services
 Network File System (NFS)
 Softcopy Services
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
11
New Features In z/OS
Version 1, Release 2

HiperSockets
 TCP/IP Networking enhancements
 Internet and Intranet Security enhancements
 Distributed Print
 New File System and C++ compiler
 Intelligent Resource Director (IRD)
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
12
Chapter 2

OS/390 and z/OS concepts and terms
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
13
Objectives

Applied objective


Assign an appropriate name to a new data set.
Knowledge objectives

Identify what an address space is.

In general terms, explain how address spaces are used to implement
virtual storage and multiprogramming.
In general terms, explain how paging is used to transfer portions of an
address space to and from real storage.
In general terms, explain how swapping is used to transfer
entire address spaces in and out of virtual storage.
Identify the information contained in a volume label.
Describe the role of the VTOC in processing DASD
data sets.
Describe the three data set organizations that are
most commonly used today: sequential, partitioned,
and VSAM key-sequenced.
Distinguish between master and user catalogs.
Describe how the high-level qualifier in a data set name
is commonly used.
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© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
14
Objectives (2)

Knowledge objectives (Continued)
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
Describe unit allocation, volume allocation, and data set allocation.
List and describe the three types of open modes that can be used to
open a file.
Distinguish between a job and a job step.
Identify the basic functions of the JOB, EXEC, and DD JCL statements.
Describe the basic function of a Job Entry Subsystem.
Name the five steps that are involved in processing a job.
Describe how the job class and priority affect the
scheduling of a job.
Describe the four types of SYSOUT data that are
produced by most jobs: the JES message log, the JCL
listing, the system message log, and program output.
Describe how the output class affects the handling
of SYSOUT data set.
Distinguish between system generation and
system initialization.
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
15
Address spaces

Address space
Key Concepts
Addressable
storage locations
Processor
Main
storage
CPU
Figure 2-01a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
16
Multiple Virtual Storage

Uses DASD to Expand Memory
Page frames
Address
space 1
Real
storage
Address
space 3
Address
space 2
Address
space 4
2GB
4K
page
Expanded
storage
(S/390
processors)

Page
data set
(DASD)
8GB
2GB
2GB
2GB
2GB
Active
pages
Figure 2-02a
Page slots
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
17
Address Space Swapping

Locating The Pages
Page data
sets
Address
space 1
(swapped in)
Swap data
sets
Real storage
Address
space 2
(swapped in)
Address
space 3
(swapped in)
Address
space 4
(swapped in)
Address
space 5
(swapped out)
Address
space 6
(swapped out)
Address
space 7
(swapped out)
Address
space 8
(swapped out)
CPU
Figure 2-03a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
18
A Virtual Storage Address Space
Virtual storage
Extended LSQA, SWA, and
subpool 229/230
2GB


Unallocated storage
Extended
private area

Extended user region
Extended
common area
Extended SQA, PLPA,
and CSA

Extended nucleus
16MB
Nucleus
Common area
SQA, PLPA, and CSA

LSQA, SWA, and
subpool 229/230
Private
area
Unallocated storage
User region
System region
Two Basic Areas
 The Private Area
 The Common Area.
Special Provisions For The First
16mb Of Address
Common Areas Have Two
Sections.
 Above The 16MB Line
 Below It.
Common Area Contains
 The Nucleus
 Other Operating System Data.
The Private Area Contains
 Data Unique To Each User’s
Address Space
 The Program Being Executed.
0MB
Figure 2-04a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
19
Dataspaces And Hiperspaces On
A System

Definitions
Address space
Dataspace
Real
storage
Hiperspace
Expanded
storage
4KB blocks

Figure 2-05a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
20
DASD Labels Identify Files On A
Volume
Disk
volume
VOL1 label
VTOC
VTOC
FILE-A
FILE-B
FILE-C
FILE-B
Free
extents
Free extent
FILE-A
FILE-B
FILE-C
Free extent
FILE-B
Free extent
Figure 2-06a



z/OS identifies data sets on DASD with labels.
DASD volumes contain a volume label,
The VTOC (Volume Table of Contents) contains labels called
Data Set Control Blocks, or DSCBs,
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
21
Rules For Forming Data Set
Names





Length
1 to 44 characters (standard)
1 to 35 characters (generation data group; see chapter 12)
Only first 17 characters are used for tape data sets
Characters
Alphanumeric (A-Z, 0-9)
National (@,#, and $)
Period (.)
Qualifiers
Data set names with more than 8 characters broken into
qualifiers
1 to 8 characters. Separate qualifiers with periods.
First character
The first character of each qualifier must be a letter or
national character.
Last character
The last character of a data set name should not be a period.
A valid data set name
AR.TRANS.Y2001
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
22
File Organization
A file with sequential organization by employee
number
Disk
location
1
2
3
4
5
Social
Security
number
First name
498-27-6117
213-64-9290
279-00-1210
499-35-5079
334-96-8721
Thomas
William
Constance
Ronald
Marie
Employee
Middle
initial Last name number
T
J
M
L
Bluestone
Collins
Harris
Garcia
Abbott
01003
01054
01702
02145
02181
A file with VSAM key-sequenced organization,
indexed by employee number
Index component
Employee Disk
number
location
01003
01054
01702
02145
02181
1
2
3
4
5
Data component
Disk
location
1
2
3
4
5
Social
Security
number
498-27-6117
213-64-9290
279-00-1210
499-35-5079
334-96-8721
First name
Thomas
William
Constance
Ronald
Marie
Middle
initial Last name
T
J
M
L
Bluestone
Collins
Harris
Garcia
Abbott
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
Employee
number
01003
01054
01702
02145
02181
Figure 2-07a
23
Partitioned Data Set With Three
Members
Data set name: MM01.TEST.COBOL
Directory
PAY1000
PAY2000
PAYTRAN
...
Member PAY1000
*
*
*
*
*
IDENTIFICATION DIVISION.
Member PAYTRAN
PROGRAM-ID. PAY1000.
ENVIRONMENT DIVISION.
*
01
INPUT-OUTPUT SECTION.
FILE-CONTROL.
.
.
.
SELECT PAYMAST ASSIGN TO PAYMAST.
PAYROLL-TRANSACTION-RECORD.
05
05
05
05
05
PT-EMPLOYEE-NUMBER
PT-TRAN-DATE
PT-TRAN-SERIAL
PT-TRAN-TYPE
PT-TRAN-AUTHORIZATION
PIC
PIC
PIC
PIC
PIC
9(6).
9(6).
9(7).
X.
99.
Member PAY2000
*
*
*
*
*
IDENTIFICATION DIVISION.
PROGRAM-ID. PAY2000.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
.
.
.
SELECT PAYTRAN ASSIGN TO PAYTRAN.
Figure 2-08a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
24
Catalog Structure

The relationships among the master catalog, user
catalogs, and data sets
Master
catalog
VSAM
data sets
User
catalogs
Non-VSAM
data sets
Figure 2-09a
VSAM
data sets
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
Non-VSAM
data sets
25
The EBCDIC Codes For
Alphanumeric Characters
Character Hex
space
.
(
+
&
$
*
)
;
-
40
4B
4D
4E
50
5B
5C
5D
5E
60
Character Hex
A
B
C
D
E
F
G
H
I
C1
C2
C3
C4
C5
C6
C7
C8
C9
Character Hex
J
K
L
M
N
O
P
Q
R
D1
D2
D3
D4
D5
D6
D7
D8
D9
Character Hex Character Hex
S
T
U
V
W
X
Y
Z
E2
E3
E4
E5
E6
E7
E8
E9
0
1
2
3
4
5
6
7
8
9
F0
F1
F2
F3
F4
F5
F6
F7
F8
F9
Figure 2-10b
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
26
The Three Levels Of Data Set
Allocation

Level 1: Unit allocation




generic name or group name.
A generic name an IBM-supplied name indicating a device type
A group name, or esoteric name, flexible way to allocate units.
Level 2: Volume allocation


Volume serial number (vol-ser).
Non-specific volume request


Non-specific volume requests aren’t valid for existing data sets.
Level 3: Data set allocation

For new data sets, file labels are created, space allocated, and
the VTOC is updated.
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
27
How Data Sets Are Processed
OS/390
Program
I/O requests
Read
Data set
open modes
Access methods
Input
QSAM
Write
Output
Data
VSAM
Read/
Rewrite
I/O
Figure 2-12a
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
28
What This Course Is About



Jobs
Job Control Language JCL
JES
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
29
Three Basic JCL Statements



JOB
EXEC
DD
information that identifies the job.
Indicates the program to be executed.
Identifies a file to be processed.
JCL statements for a job that prints a report
//MM01RN JOB (36512),'R MENENDEZ',NOTIFY=MM01
//RPTRUN EXEC PGM=RPT3000
//CUSTMAST DD
DSNAME=MM01.CUSTOMER.MASTER,DISP=SHR
//SALESRPT DD SYSOUT=A
//ERRLIST DD SYSOUT=A
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
30
How JES2 and JES3 process jobs

How a job enters the system


Entering JCL commands into a display terminal.
Terminal user issues:


SUBMIT, or SUB, command
TheJES3
job is then copies it to the queue
The job’son the JES spool.
JES2 or
The job is
The job is
selected
submitted
Scheduling
forforexecution
executed
execution


output is
processed
The job is
purged
JES examines jobs in the queue and prioritizes the work.
Job class and priority classify
a job’s importance.
Figure 2-13b


An initiator program runs in the system region of an address
space eligible for batch job processing.
Each initiator can handle one job at a time.
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
31
Job Classes

Typical job class assignments

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


Job class Characteristics
A
Execute within 15 minutes of submission.
B
Execute within 30 minutes of submission.
C
Execute within 1 hour of submission.
D
Execute overnight.
H
Hold until released by an operator.
L
Execute within 15 minutes of submission


Each step is limited to 1 minute of execution time.
How job classes are assigned to initiators





Initiator
1
2
3
4
Eligible job classes
A
B,C,D,H,L
B,C
C
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
32
How A Job Is Executed Once An
Initiator Selects It
Private area
Local system areas
Control blocks
Private area
Local system areas
Control blocks
Private area
Local system areas
Control blocks
Private area
Local system areas
Control blocks
User program
System region
System region
System region
System region
Interpreter
Allocation
Unallocation
Initiator
After the initiator
selects a job for
execution, it invokes
the interpreter, which
builds the required
control blocks in the
address space’s
SWA.
Initiator
Initiator
For each job step, the
initiator invokes
allocation routines to
allocate the units,
volumes, and data
sets required by the
job step.
After the job step’s
resources have been
allocated, the initiator
creates a user region,
loads the user
program into it, and
transfers control to the
user program.
Figure 2-15
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
Initiator
When the user
program completes,
the initiator invokes
unallocation routines
to deallocate the
resources used by the
job step. Then, if the
job has more steps,
the initiator repeats
the allocationexecution-unallocation
process.
33
OUTPUT Controls

The SYSOUT data sets produced by most jobs

SYSOUT data set
JESMSGLG

JESJCL

JESYSMSG

SYSOUT


Description
A listing of messages produced by JES2 or JES3
as the job was executed.
The JES JCL listing is a listing of the JCL
processed by the job.
The system message log is a collection of
message produced as the job was executed.
SYSOUT data produced by a program executed
in the job.
Typical output class assignments




Output class
A
B
X
Type of output
Standard printer output, routed to one of the
installation’s high-speed printers
Special printer output.
Held output that stays on the SYSOUT queue
until released for printing or deleted.
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
34
SYSGEN

System generation


System generation (sysgen) creates the system.
IBM sends or Downloads distribution libraries.



System generation selects and assembles
components needed to create a working system.
Systems programmer codes special macro
instructions specifying how components
should be put together.
The output is a series of system libraries
containing, the executable code that makes up
the operating system.
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
35
Initialization

System initialization

The process of starting a previously generated
system



Immediately after sysgen
Reinitialized due to system maintenance or a system
error.
Operator uses the system console to start
an Initial Program Load, or IPL.


System clears its real storage
Loads the operating system from the system
libraries
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
36
End Presentation
© 2002 - Mike Murach & Associates,
2007 - HCC, IBM
37