Stephen Linkin Houston Community College January 15, 2007 © Mike Murach & Associates, HCC, IBM 1 Introduction To IBM Mainframe Systems Chapter 1-2 Review

2 Objectives Identify Basic Components Of Mainframe Processors Identify Difference In Architecture IBM’s z/Series Processors And Earlier Systems Types Of I/O Devices On Mainframes Define Tracks And Cylinder Describe Features Of Mainframe OS: V Virtual Storage M Multiprogramming Spooling Batch Processing Time Sharing. Describe MVS, OS/390, And Z/Os

© Mike Murach & Associates, HCC, IBM3 Figure 1-01a The z/OS Redbook Shows How It Evolved Into--- The Basic Architecture For IBM Mainframe Systems

© Mike Murach & Associates, HCC, IBM4 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)

5 Direct access storage devices, or DASD Tape Drives and Optical Disks Display And Other Terminals Printers I/O Devices That Connect To Mainframe Servers

6 Figure 1-08a Virtual Storage An overview of virtual storage and multiprogramming

© Mike Murach & Associates, HCC, IBM7 Figure 1-09a Spooling How the operating system spools output from application programs

© Mike Murach & Associates, HCC, IBM8 Figure 1-10a Batch Processing Job Control Language How batch processing works

© Mike Murach & Associates, HCC, IBM9 Figure 1-11a Time Sharing Multiple users in a time sharing environment

© Mike Murach & Associates, HCC, IBM10 Figure 1-12a Time Line The evolution of the OS/390 and z/OS operating system

© Mike Murach & Associates, HCC, IBM11 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

© Mike Murach & Associates, HCC, IBM12 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)

© Mike Murach & Associates, HCC, IBM13 OS/390 and z/OS concepts and terms Chapter 2

© Mike Murach & Associates, HCC, IBM14 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.

© Mike Murach & Associates, HCC, IBM15 Objectives (2) Knowledge objectives (Continued) 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.

© Mike Murach & Associates, HCC, IBM16 Figure 2-01a Address spaces Key Concepts

© Mike Murach & Associates, HCC, IBM17 Uses DASD to Expand Memory Figure 2-02a Multiple Virtual Storage

© Mike Murach & Associates, HCC, IBM18 Locating The Pages Figure 2-03a Address Space Swapping

© Mike Murach & Associates, HCC, IBM19 Figure 2-04a A Virtual Storage Address Space 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.

© Mike Murach & Associates, HCC, IBM20 Figure 2-05a Dataspaces And Hiperspaces On A System Definitions

© Mike Murach & Associates, HCC, IBM21 Figure 2-06a DASD Labels Identify Files On A Volume z/OS identifies data sets on DASD with labels. z/OS identifies data sets on DASD with labels. DASD volumes contain a volume label, DASD volumes contain a volume label, The VTOC (Volume Table of Contents) contains labels called Data Set Control Blocks, or DSCBs, The VTOC (Volume Table of Contents) contains labels called Data Set Control Blocks, or DSCBs,

© Mike Murach & Associates, HCC, IBM22 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. Rules For Forming Data Set Names A valid data set name AR.TRANS.Y2001

© Mike Murach & Associates, HCC, IBM23 Figure 2-07a File Organization

© Mike Murach & Associates, HCC, IBM24 Figure 2-08a Partitioned Data Set With Three Members

© Mike Murach & Associates, HCC, IBM25 The relationships among the master catalog, user catalogs, and data sets Figure 2-09a Catalog Structure

© Mike Murach & Associates, HCC, IBM26 Figure 2-10b The EBCDIC Codes For Alphanumeric Characters

© Mike Murach & Associates, HCC, IBM27 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.

© Mike Murach & Associates, HCC, IBM28 Figure 2-12a How Data Sets Are Processed

© Mike Murach & Associates, HCC, IBM29 What This Course Is About Jobs Job Control Language JCL JES

© Mike Murach & Associates, HCC, IBM30 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 JOBinformation that identifies the job. EXECIndicates the program to be executed. DD Identifies a file to be processed. Three Basic JCL Statements

© Mike Murach & Associates, HCC, IBM31 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 JES2 or JES3 then copies it to the queue on the JES spool. Scheduling for execution JES examines jobs in the queue and prioritizes the work. Job class and priority classify a job’s importance. 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. Figure 2-13b

© Mike Murach & Associates, HCC, IBM32 Job Classes Typical job class assignments Job classCharacteristics AExecute within 15 minutes of submission. BExecute within 30 minutes of submission. CExecute within 1 hour of submission. DExecute overnight. HHold until released by an operator. LExecute within 15 minutes of submission Each step is limited to 1 minute of execution time. How job classes are assigned to initiators InitiatorEligible job classes 1A 2B,C,D,H,L 3B,C 4C

© Mike Murach & Associates, HCC, IBM33 Figure 2-15 How A Job Is Executed Once An Initiator Selects It

© Mike Murach & Associates, HCC, IBM34 OUTPUT Controls The SYSOUT data sets produced by most jobs The SYSOUT data sets produced by most jobs SYSOUT data setDescription SYSOUT data setDescription JESMSGLGA listing of messages produced by JES2 or JES3 as the job was executed. JESMSGLGA listing of messages produced by JES2 or JES3 as the job was executed. JESJCL The JES JCL listing is a listing of the JCL processed by the job. JESJCL The JES JCL listing is a listing of the JCL processed by the job. JESYSMSGThe system message log is a collection of message produced as the job was executed. JESYSMSGThe system message log is a collection of message produced as the job was executed. SYSOUT SYSOUT data produced by a program executed in the job. SYSOUT SYSOUT data produced by a program executed in the job. Typical output class assignments Typical output class assignments Output classType of output Output classType of output AStandard printer output, routed to one of the installation’s high-speed printers AStandard printer output, routed to one of the installation’s high-speed printers BSpecial printer output. BSpecial printer output. XHeld output that stays on the SYSOUT queue until released for printing or deleted. XHeld output that stays on the SYSOUT queue until released for printing or deleted.

© Mike Murach & Associates, HCC, IBM35 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.

© Mike Murach & Associates, HCC, IBM36 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

© Mike Murach & Associates, HCC, IBM37 End Presentation