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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 Types Of I/O Devices On Mainframes Define Tracks And Cylinder Describe Features Of Mainframe OS: 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 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. © 2002 - Mike Murach & Associates, 2007 - HCC, IBM 14 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. © 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 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