Ch3-zOS功能概述

第3章:z/OS功能概述大型主机操作系统基础本章内容扩展的分区数据集-PDSEWhatisbatchprocessing?•Muchoftheworkrunningonz/OSconsistsofprogramscalledbatchjobs.•Batchprocessingisusedforprogramsthatcanbeexecuted:–Withminimalhumaninteraction–Atascheduledtimeoronanas-neededbasis.•Afterabatchjobissubmittedtothesystemforexecution,thereisnormallynofurtherhumaninteractionwiththejobuntilitiscomplete.WhatisJES?•Inthez/OSoperatingsystem,JESmanagestheinputandoutputjobqueuesanddata.•JEShandlesthefollowingaspectsofbatchprocessingforz/OS:–Receivejobsintotheoperatingsystem–Schedulethemforprocessingbyz/OS–Controltheiroutputprocessing.WhatisJES?(continued)•z/OSofferstwotypes:JES2andJES3•Someimportantdifferences,butbothJES2andJES3:–Acceptandqueuejobssubmittedforexecution–Queuejobsforaninitiator--aJESprogramthatrequeststhenextjobinthequeue–Acceptoutputfromajobwhileitisrunningandqueuetheoutput–Canprinttheoutput,orsaveitonspoolforanoutputmanagertoretrieve.Batchflow(simplified)Initiator-Allocation-Execution-CleanupJOBsJCLProcessingJESSPOOLSPOOLInitiator-Allocation-Execution-CleanupsubmitPrinterWhatisspooling?•Spoolingisameansofqueuingandholdingdataforinputoroutput.•JESusesoneormorediskdatasetsforspooling.•Inputjobsandprintedoutputfrommanyjobsarestoredinthesingle(conceptual)spooldataset.Whataninitiatordoes•Torunmultiplejobsasynchronously,z/OSusesinitiatorsto:–Ensurethatjobsdonotconflictindatasetusage–Ensurethatsingle-userdevices(tapedrives)areallocatedcorrectly–Findexecutableprogramsrequestedbyjobs–Cleanupafterthejobendsandrequestthenextjob.•Preventingtwousersfromaccessingthesamedataatthesametimeiscriticaltoz/OSandtheabilitytodothisisoneofthedefiningcharacteristicsoftheoperatingsystem.Symbolicfilesystem•z/OSnormallyusesasymbolicfilesystem,whichappliesanamingredirectionbetweenadataset-relatednameusedinaprogramandtheactualdatasetusedduringexecutionofthatprogram.HowasymbolicfilesystemisusedOPENFILE=XYZREADFILE=XYZ...CLOSEFILE=XYZprogramDDNAMEJCLforJOBDSNAME//XYZDDDSNAME=MY.PAYROLLMY.PAYROLLHowasymbolicfilesystemisused(continued)OPENFILE=XYZREADFILE=XYZ...CLOSEFILE=XYZprogramDDNAMEJCLforJOBDSNAME//XYZDDDSNAME=DIV1.PAYROLLDIV1.PAYROLLJES,jobmanagement,andJCL•JobcontrollanguageorJCListhelanguageusedbyabatchjobtorequestresourcesandservicesfromtheoperatingsystem.•ThroughJCL,youspecify:–Whoyouare(importantforsecurityreasons)–Whichresources(programs,files,memory)andservicesareneededfromthesystemtoprocessyourprogram.•TheuseofJCLiscoveredindetailinthenextmodule.RelatedactionswithJCLITUSERACTIONSSYSTEMACTIONSDeterminetheneedandcharacteristicsoftheJobCreatetheJCLSubmittheJobJESinterpretsJCLandpassesittoz/OSinitiatorz/OSmanageseachstepofexecutionJESprintsoutputJEScollectstheoutputandinformationabouttheJobUserviewsandinterpretsoutputSystemMessagesSpoolingspool33programSYSOUTwrite22readJCL//DD1DD*/*//DD2DDSYSOUT=A厖...............data厖...............//DD1DD*/*//DD2DDSYSOUT=A厖...............data厖...............//DD1DD*/*//DD2DDSYSOUT=A厖...............data厖...............11JESPrinter44JESTwo-stepjobFirststepProgramTapeUpdatesProgramPrinterMasterMasterMasterSecondstepOverviewofRACF