setting the interval control values in cics在cics设置间隔控制值

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1、SettingtheIntervalControlValuesinCICSCICShasthreeintervalcontrolvaluesthatarespecifiedintheSystemInitializationTable(SIT),viaoverridesorthroughtheuseofCEMTcommandtosetanewvalue.SettingtheseparameterscorrectlycanhelpreducesystemCPUoverheadandprovideabetterus

2、eofresources.ThisisespeciallytrueininstallationsthathavemanyCICSregions.Thisarticleexplorestheseparametersandprovidesrecommendationsastowhatvaluesshouldbeused.Thethreeparametersandabriefdescriptionareasfollows:·IntervalControlValue(ICV)–usedtospecifythemaxi

3、mumamountoftimeCICSistowaitwhenthereisnoworktodo,thatis,noreadytasktodispatchwithinCICS.Thetimeisgiveninmillisecondsandthedefaulttimeis1000ms.oronesecond·IntervalControlValueforRunawayTasks(ICVR)–usedtospecifythemaximumamountofrealCPUtimethatisallottedtoata

4、skbeforethetaskhastoreturncontroltoCICSorelsethetaskiscancelledwithacancelcodeofAICA.Thetimeisgiveninmillisecondsandthedefaulttimeis5000ms.orfiveseconds·IntervalControlValueforTerminalScanDelay–usedtospecifytheamountoftimethatistoelapsebeforeCICSdealswithso

5、meterminalI/Oactivity.Thetimeisgiveninmillisecondsandthedefaultis500ms.orhalfasecondLetusaddresstheICVparameterfirst.WhenCICShasnotransactionreadytodispatchorworktodo,CICSentersawaitstatebasedonanECBlistthatincludestheICVtimer.AnyinterruptthatpostsanECBcomp

6、letionwakesCICSeveniftheICVtimerECBhasnotcompleted.TraditionalrecommendationsspecifythattheICVcanbeusedtoprotecttheworkingsetoftheCICSregion.PeriodsoflowterminalortransactionactivitycanrepresentaproblemforCICSifthesystemisunderpressureforrealstorage.Setting

7、theICVtoalowvaluesuchas1000ms.(1second)willwakeupCICSmoreoftentotryandprotectpartofthenucleus.However,wakingupCICSthisoftentofindnothingtodispatchandtobeplacedintoawaitstateagaincanbeawasteofCPUresources.ItisimportanttonotethatCICSisaverydisperseon-linesyst

8、emthatrequiresalotofrealstoragetoexecute.DuringnormaltransactionexecutionmanyCICSmanagementprograms,controlblocksandtablesmustbeaccessedinadditiontotheuserprogramandstorageareas.So,wakingCICSoftenasare