主机复习题库132题问答.docx

主机复习题库132题问答.docx

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主机复习题库132题问答

1）what'smainframe?

Mainframessystemsaredesignedforlargeamountsofdatainmanydifferentandinterconnectedways.

Mainframeisamachinethatrunsamainframeoperatingsystem.IntheIBMworld,thisoperatingsystemisz/OS,OS/390,MVS/ESA,VM/ESAandVSE/ESA.

2）what'stheadvantageofmainframe?

reliability,recoverability,redundancy,safty,connectivity,concurrency

3）what'sOS/390?

OS/390isanew,integratedenterpriseserveroperatingsystemenvironment.Itincorporatesintooneproductaleading-edgeandopencommunicationserver,distributeddataandfileservices,parallelsysplexsupport,object-orientedprogramming,DCEandopenapplicationinterfaces.

4）what'stheOS390'Selements?

DFSMS,SDSF,TSO,ISPF,DITTO,NETVIEW,SDFII,VTAM,JES2,RACFetc...

5）what'sthesysplex?

SYSPLEXisacollectionofMVSsystemsthatcooperate,usingcertainhardwareandsoftwareproducts,toprocesswork.

6）howmanytypephysicalstoragearethereinmainframe?

CentralStorage（MainStorage）

ExpandedStorage

AuxiliaryStorage

7）what'sjes2?

Ajobentrysubsystem（JES）isresponsibleformanagingjobsinanOS/390system.

8）what'sjobprocessstage?

Input

Conversion

Execution

Output

Hardcopy

Purge

9）what'scataloginmainfram?

Mastercatalogisthecatalogthatlistsalltheusercatalogs,systemdatasetsandtheirlocations.

Usercatalogisthecatalogthatcanbeaccessedandchangedbyusers.Itholdstheuserdatasets.

Thereareone,andonlyone,mastercatalog.

Thesearchorderofcatalogis:

STEPCATinjob

JOBCATinjob

AliasesinUserCAT

Mastercatalog

10）HowmanytypeareThereseveraltypesofDUMP?

SYMPTOMDUMP

SNAPDUMP

SYSDUMP

SYSMDUMP

SVCDIMP

STAND-ALONEDUMP

11）what’sISPF?

ISPF（InteractiveSystemProductivityFacility）isPDF（ProgramDevelopmentFacility）'sprerequisitelicensedprogram.ISPFmustbeinstalledeitherbeforeorduringtheinstallationofPDF.

12）WhatisJCL?

JCLstandsforJobControlLanguage,JCLisasetofcontrolstatementthatprovidethespecificationnecessarytoprocessajob.

13）Whatisthedifferencebetweenkeywordandpositionalparameters?

Positionalparametersarecharacterizedbytheirpositionintheoperandfieldinrelationtootherparameters.

Keywordparametersarepositionallyindependentwithrespecttoothersoftheirtypeandconsistingofakeywordfollowedbyanequalsignandvariableinformation.

14）WhatisaDISP?

DISPisakeywordparameterwhichisdefinedontheDDstatementandwhichconsistofthefollowingpositionalsubparameters:

DISP=（Status,NormalDisp,AbnormalDisp）.TheDISPparameterdescribesthecurrentstatusofthedataset（old,new,ormodified）anddirectsthesystemonthedispositionofthedataset（pass,keep,catalog,uncatalog,ordelete）eitherattheendofthesteporifthestepabnormallyterminates.DISPisalwaysrequiredunlessthedatasetiscreatedanddeletedinthesamestep.

15）WhatisDISP=SHR?

DISP=SHRpermitsolddatasetstobeshared.SHRisidenticaltoOLDexceptthatseveraljobsmayreadthedatasetconcurrentlyinmultiprogrammingenvironments.SHRmustbeusedonlyforinputdatasets;useOLDorMODifdatasetismodified.?

SharingdatasetisnecessarybecausepubliclibrarieslikeSYS1.LINKLIBorthesubroutinelibrariesshouldbeavailabletoeveryjobinthesystem.

16）WhatisDISP=MOD?

DISP=MODmodifiesasequentialdataset.Itisaconvenientwaytoadddatatotheendofsequentialdataset.Ifthedatasetdoesn'texist,thesystemchangesMODtoNEWunlesstheVOLparameterrequestspecificvolume.WhenVOLiscoded,thestemexpectstofinddatasetonthespecifiedvolumeandterminatesthestepifitcannotfindit.MODistheusualwayofextendeddatasetsintoseveraldirect-accessvolumes.

17）WhatisDISP=PASS?

PASSpassesthedatasetontosubsequentjobsteps,andeachstepcanusethedatasetonce.ItisapositionalsubparameteroftheDISPwhichcouldonlybespecifiedundernormalterminationaction.Passsavestimebecausethesystemretainsthedatasetlocationandvolumeinformation.

18）WhataretheparametersthathavetobecodedonaDDstatementinordertoretrieveacatalogeddataset?

TheminimumparametersneededareDSNandDISP.

19）Howdoesthesystemgetinformationabouttheblocksize?

DCBinfocomesfrom:

-

1）Program-FD:

BLOCKCONTAINS3RECORDSRECORDCONTAINS100CHARACTERS

2）Thelabel-likeatape

3）FromtheVTOC-forDasd

4）FromtheJCL-DCB=BLKSIZE=nnn.

20）WhatisaLabel?

LABELisakeywordparameterwhichcanbespecifiedonDDstatementandconsistsofthefollowingsubparameters:

LABEL=（RelativeFile#,TypeofLabelProcessing）

TheLABELparametertellsthetypeoflabel,therelativefilenumber,andwhetherthedatasetistobeprotectedforinputoroutput.

21）WhenshouldbeNLbespecifiedasatypeoflabelprocessing?

NLshouldbespecifiedwhenaprogramneedstoprocessunlabeledtapesNLcanalsobespecifiedwhenthepgmwantstocreateunlabeledtapebecausethesystem'sdefaultaction,incaseswhenparameterisnotspecified,willcreateIBMstandardlabel.Nonlabeledtapesareoftenusedforsendingtapestoanotherinstallation.Thatwayyoudon'thavetoworryaboutthetapelabelcorrespondingtothestandardsattheotherinstallationoraboutaccidentallymatchingthevolumeserialnumberofanexistingtapeattheinstallation.

22）Howdoyoudescribetheinputdatawhichisapartoftheinputjobstream?

YoushoulduseeitherDD*orDDData.

23）Whatisthedifferencebetween*andData?

DD*andDDDATAdescribetheinputdatawhichfollowstheabovementioncards.Iftheinputdatacontainsrecordswitch//incol1and2thenDDDatashouldbeused.

24）WhatisthepurposeofSPACEparameter?

ItisakeywordparameterwhichshouldallocatedontheDDstatementfortheoutputdatasetsstoredonthedisk.Itconsistsofthefollowingsubparameters:

SPACE=（BLKS/CYL/TRK,（primary,secondary,index）,RLSE,CONTIG）

25）WhatisaRLSE?

RLSEreleasesallunusedspacewhenthedatasetisclosed.Itpermitsyoutoallocatemorespacethanperhaps,itneededwithoutwastingspace.Spaceisreleasedonlyifthedatasetisnotemptyandifthedatasetisclosedafterbeingopened.

26）WhatisaCONTIG?

CONTIGrequeststheprimaryspacebeallocatedonlyoncontiguoustracksandcylinders,thatisalltracksonacylinderarecontiguous,andifmorethanonecylinderisneeded,thecylindersarealsocontiguous.AlwayscodeCONTIGiftrackoverflowisused.

27）WhatisaPDS?

PDSisalibrarytypeofdatasetorganizationconsistingofDirectoryandMembers.Thedirectoryconsistsofblocks,andeachblockis256bytesinlengthandcanholdupto5members.EachmemberofthePDSisasequentialdataset.

28）WhatisaTemporaryDataSet?

Temporarydatasetsareusedforstorageneededonlyforthedurationofthejob.IftheDISPparameterdoesn'tdeletethedatasetbytheendofthejob,thesystemwilldeleteit.Deletingatapedatasetdismountsthetape,whereasdeletingadatasetonadirect-accessvolumereleasethestorage.AdatasetismarkedtemporarybyomittingtheDSNparameterorbycodingDSN=&&dsname.ThesystemassignauniquenametothedatasetwhentheDSNparameterisomitted,andanysubsequentstepsusingthedatasetreferbacktotheDDstatement.

29）WhatisCONDparameter?

ItisakeywordparameterwhichcanbespecifiedontheJOBorEXECstatements.CONDconsistsof3subparameters:

code（0thru4095）,logicaloperator,andstepnameofthestepthatisgoingtobecompared.

ThepurposeoftheCONDistodeterminewhetherthestepshouldbeexecutedorbypassed.IfconditionspecifiedintheCONDparameteristrue,thestepisbypassed.

30）HowdoyouspecifyaCONDparameterforajobstepsothatthestepwillneverbeexecuted?

COND=（0,LE）orCOND=（4095,GE）.

31）WhatdoesCOND=ONLYmean?

Itmeansthatthisjobstepwillbeexecutedonlyifapreviousstephadabnormallyterminated.

32）WhatdoesCOND=EVENmean?

Itmeansthatthisjobsstepwillbeexecutedevenifapreviousstepabnormallyterminated.

33）WhatisaNAME?

Nameisapositionalparameterwhichidentifiesthepersonorgroupresponsibleforajob.

34）WhatisaPRIORITY?

Itisakeywordparameterwhichspecifiesajobinitiationprioritywithinitsjobclass.Whenthejobisinitiated,thesystemwillconvertthejob'spriorityintoadispatchingprioritysothatjob'staskcancompletewithothertasksforuseofmainstorageandCPUresources.

35）Howdoesthesystemdeterminethepriorityofajobforexecution?

Firstthesystemdetermineswhichjobhasthehighestclass.Eachclasshasajobqueuewithjobsofdifferentpriorities.ThesystemwillselectthejobforexecutionthathasthehighestPRTY（0thru15）15isthehighestpriority.

36）WhatisaMSGCLASSparameter?

Itisakeywordparameterwhichspecifiestheoutputclasstowhichsystemmessagesforyourjobaretoberouted.Outputclassisanalphabetic（AthruZ）ornumeric（0thru9）character.ThedefaultforMSGCLASSparameterwillbeA.Systemmessagesandoutputdatasetscanberoutedtothesameoutputclass.YoucancodetheMSGCLASSparameterintheJobstatementandtheSYSOUTparameterontheDDstatement.

37）WhatisMSGLEVELparameter?

Itisakeywordparameterwhichindicateswhatjoboutputistobewrittenasapartofoutputlisting.Thefollowingoutputscanberequested:

theJobstatement;

allinputjobcontrolstatements;

allocation,dispositionandallocationrecoverymessages（allocation/terminationmessage）

MSGLEVEL=（statements,messag