JCL经典面试题库

JCL经典面试题库2009年03月16日 | 5:14 下午分类：大型机Mainframe|标签：JCL、大机、文档资料、笔试、面试、题库|JOB CONTROL LANGUAGE(JCL)The following are the most Frequently Asked Questions (FAQS) :Q1) What is a Generation Data Group (GDG)?A1) Generation Data Group is a group of chronologically or functionally related datasets. GDGs are processed periodically, often by adding a new generation, retaining previous generations, and sometimes discarding the oldest generation.什么是GDG？GDG是一组按世代或功能划分的数据集。GDG按世代处理，加一个新的一代数据要受上一代的限制，有时会丢换最老的一代。Q2) How is a GDG base created?A2) A GDG base is created in the system catalog and keeps track of the generation numbers used for datasets in the group. IDCAMS utility is used to define the GDG base.GDG BASE 怎么样创建？GDG BASE在系统编目时被创建并且在GDG中保留用于DATASET中的世代个数的空间。使用IDCAMS定义GDG BASE。（来源：/）Q3) What is model dataset label(Model DSCB)?A3) A model dataset label is a pattern for the dataset label created for any dataset named as a part of the GDG group. The system needs an existing dataset to serve as a model to supply the DCB parameters for the generation data group one wishes to create. The model dataset label must be cataloged. The model DSCB name is placed on the DCB parameter on the DD statement that creates the generation data group.什么是MODEL DSCB？ MODEL DSCB是为GDG里的部分DATASET名创定标签。系统需要一个存在的DATASET做为一个模型向你想创建的GDG提供DCB参数。该模型DATASET标签必须被编目，MODEL DSCB名放在创建GDG的DD语句中的DCB参数中。Q4) How are GDGs concatenated?A4) Generation Data Groups are concatenated by specifying each dataset name and the generation number for all generations of the generation data group. Otherwise to have all generations of a generation data group, omit the generation number. The DD statement will refer to all generations. The result is the same as if all individual datasets were concatenated. If generations are not on the same volume, this will not work.GDG怎么样级联？GDG级联既可以指定每一个DATASET名，也可以指定GDG里的世代个数。另外，级联GDG里的所有世代可以省略世代个数。DD语句将涉及到所有的世代。结果和一个一个的级联一样。如果世代不在同一个卷上该命令将不起作用。Q5) How is a new GDG coded?A5) A new GDG is coded as (+1) after the dataset name as follows: DSN=JAN.DATA(+1). This will cause all generations to be pushed down one level at the end of the job.怎么编写GDG？一个新的子代GDG在DATASET名后加个（+1），例如：DSN=JAN.DATA(+1)将使所有的世代数据都向上升一代（个人理解）。并将该代数据放在最后一代。Q6) When should DISP=MOD is used?A6) DISP=MOD is used to either extend an existing sequential dataset or to create a dataset if it does not exist. If the dataset exists, then records are appended to the dataset at the end of the existing dataset. If the dataset does not exist, the system treats MOD as if it were NEW, provided that the volume parameter has not been used. If the volume parameter is used, the system terminates the job and does not create the new dataset. MOD can be used to add to a dataset that extends onto several volumes. Always specify a disposition of CATLG with MOD for cataloged datasets, even if they are already cataloged, so that any additional volume serial numbers will be recorded in the catalog.、什么时候使用DISP=MOD？DISP=MOD既可以扩展一个顺序DATASET，也可以创建一个没有存在的DATASET，对于一个存在的DATASET，记录被追加到末尾。如果没存在系统将把MOD当成NEW看，提供一个没有使用的空间参数。如果空间参数使用过了，系统则终止JOB并且不创建DATASET，MOD可以被用来扩展一个DATASET的空间。经常用MOD为一个编目的DATASET指定CATLG的属性，既使它已经编目了，因此在编目中可以增加任何连续的空间来写记录。Q7) How is a dataset passed from one step to another?A7) A dataset is passed from one step to another based on what is coded on the DISP parameter. The dataset can only be passed to subsequent steps if PASS was used on the disposition parameter.DATASET怎么从一个STEP传递到另一个STEP？传递由DISP参数决定，使用DATASET只能被传递到下一个STEPQ8) How are datasets concatenated?A8) Datasets are concatenated by writing a normal DD statement for the first dataset and then adding a DD statement without a DDNAME for each dataset to be concatenated in the order they are to be read. The following is an example of three datasets concatenated:/YEARDAT DD DSN=JAN.DATA,DISP=SHR/ DD DSN=FEB.DATA,DISP=SHR/ DD DSN=MAR.DATA,DISP=SHRDATASET怎么级联的？DATASET级联是通过先写一个一般的DD语句，然后加上一个没有DDNAME的DD语句，看读取顺序被级联。如上例所示。Q9) What is the difference between the JOBLIB and the STEPLIB statements?A9) The JOBLIB statement is placed after the JOB statement and is effective for all job steps. It cannot be placed in acataloged procedure. The STEPLIB statement is placed after the EXEC statement and is effective for that job steponly. Unlike the JOBLIB statement, the STEPLIB can be placed in a cataloged procedure.JOBLIB语句 和 STEPLIB语句有什么区别JOBLIB语句是在JOB语句之后，对于所有的steps都有效，并且不能放在编目过程中，JOBLIB语句是在EXEC语句之后，只对当前的step有效，不同于JOBLIB，它可以放在编目过程中。Q10) Name some of the JCL statements that are not allowed in procs.?A10) Some of the JCL statements which are not allowed in procedures are:1. JOB, Delimiter(/*), or Null statements2. JOBLIB or JOBCAT DD statements3. DD * or DATA statements4. Any JES2 or JES3 control statements在procs那些JCL语句不能命名在过程中不允许的JCL语句：1. JOB, 分隔符(/*), 或空语句2. JOBLIB 或JOBCAT DD语句3. DD * 或DATA语句4. 任何 JES2 或 JES3 控制语句Q11) What is primary allocation for a dataset?A11) The space allocated when the dataset is first created.一个数据集的初次分配是什么数据集建立时的空间（来源：/）Q12) What is the difference between primary and secondary allocations for a dataset?A12) Secondary allocation is done when more space is required than what has already been allocated.一个数据集的主分配和从分配有什么区别从分配是当要求更多空间时所分配的Q13) How many extents are possible for a sequential file ? For a VSAM file ?A13) 16 extents on a volume for a sequential file and 123 for a VSAM file.一个顺序文件有多少extents，VSAM？顺序文件为在一个卷上为16 extents，VSAM文件为123Q14) What does a disposition of (NEW,CATLG,DELETE) mean? - GSA14) That this is a new dataset and needs to be allocated, to CATLG the dataset if the step is successful and to delete the dataset if the step abends.(NEW,CATLG,DELETE)的意思是什么创建一个新的数据集，在作业步正常结束时编目，异常终止时删除Q15) What does a disposition of (NEW,CATLG,KEEP) mean? - GSA15) That this is a new dataset and needs to be allocated, to CATLG the dataset if the step is successful and to KEEP but not CATLG the dataset if the step abends. Thus if the step abends, the dataset would not be catalogued and we would need to supply the vol. ser the next time we refer to it.(NEW,CATLG,KEEP) 的意思是什么创建一个新的数据集，在作业步正常结束时编目然后保留在相应的卷上，异常终止时不编目。所以当作业步异常终止时，数据集不编目，并需要为下次提供相应的卷序列号Q16) How do you access a file that had a disposition of KEEP? - GSA16) Need to supply Volume Serial Number怎样才能访问一个KEEP的文件需要提供卷序列号VOL=SER=xxxx.Q17) MOD, DELETE; What does a disposition of (,DELETE) mean ?A17) The MOD will cause the dataset to be created (if it does not exist), and then the two DELETEs will cause the dataset to be deleted whether the step abends or not. This disposition is used to clear out a dataset at the beginning of a job.解释一下MOD, DELETE，(,DELETE)MOD一个新的数据集的创建（如果这个数据集不存在），2个DELETEs是无论数据集是否异常终止，都删除Disposition用于开始一个作业时删除数据集Q18) What is the DD statement for a output file?A18) Unless allocated earlier, will have the following parameters: DISP=(NEW,CATLG,DELETE), UNIT , SPACE & DCB一个输出文件的DD语句是什么如果不存在的话，则必须要有DISP=(NEW,CATLG,DELETE), UNIT , SPACE & DCBQ19) What do you do if you do not want to keep all the space allocated to a dataset? - GSA19) Specify the parameter RLSE ( release ) in the SPACE e.g. SPACE=(CYL,(50,50),RLSE)如何保持所有的分配给一数据集的空间指定参数，释放空间，如SPACE=(CYL,(50,50),RLSE)Q20) What is DISP= (NEW,PASS,DELETE)?A20) This is a new file and create it, if the step terminates normally, pass it to the subsequent steps and if step abends, delete it. This dataset will not exist beyond the JCL.解释一下DISP = (NEW,PASS,DELETE)创建一个新的数据集，如果作业步正常终止，那么保留传递到同一祖业的后续作业步中使用，如果异常终止，则删除。数据集将不再存在Q21) How do you create a temporary dataset? Where will you use them?A21) Temporary datasets can be created either by not specifying any DSNAME or by specifying the temporary file indicator as in DSN=&TEMP. We use them to carry the output of one step to another step in the same job. The dataset will not be retained once the job completes.如何建立一个临时数据集，在那里会用到他们创建了临时数据集时不需要指定的DSNAME，或用指定的临时文件DSN=&TEMP，在同一个JOB中，我们用它来？、？、在作业完成后该数据集删除Q22) How do you restart a PROC from a particular step? - GSA22) In job card, specify RESTART=PROCSTEP.STEPNAME where PROCSTEP = name of the JCL step that invoked the PROC and STEPNAME = name of the PROC step where you want execution to start在一个特殊作业步中如何restart 一个 PROC在JOB中，指定RESTART=PROCSTEP.STEPNAME ，ROCSTEP为JCL作业部的名字，执行作业步时可以调用PROC 和 STEPNAMEQ23) How do you skip a particular step in a proc/JOB? - GSA23) Can use either condition codes or use the jcl control statement IF (only in ESA JCL)如何skip 一个特殊作业步skip使用任何一个条件代码或JCL控制语句IFQ24) A PROC has five steps. Step 3 has a condition code. How can you override/nullify this condition code? - GSA24) Provide the override on the EXEC stmt in the JCL as follows:/STEP001 EXEC procname, COND.stepname=valueAll parameters on an EXEC stmt in the proc such as COND, PARM have to be overridden like this.一个PROC有5个作业步，Step 3有一个条件代码，如何erride/nullify这个条件代码在EXEC语句中用override如下：/STEP001 EXEC procname, COND.stepname=value象COND, PARM这样的EXEC语句必须这样覆盖Q25) How do you override a specific DDNAME/SYSIN in PROC from a JCL?A25) / DSN=如何覆盖一个在PROC中的特殊的DDNAME/SYSIN/ DSN=Q26) What is NOTCAT 2 - GSA26) This is an MVS message indicating that a duplicate catalog entry exists. E.g., if you already have a dataset with dsn = xxxx.yyyy and u try to create one with disp new, catlg, you would get this error. the program open and write would go through and at the end of the step the system would try to put it in the system catalog. at this point since an entry already exists the catlg would fail and give this message. you can fix the problem by deleting/uncataloging the first data set and going to the volume where the new dataset exists(this info is in the msglog of the job) and cataloging it.什么时是NOTCAT 2这是一个MVS的消息标志，它复制一个catalog entry exists，如果已经有了一个数据集dsn = xxxx.yyyy，那么当再创建一个新的时就会显示错误，程序的打开和写would go through，以及在系统的作业步的最后会试着吧它放进系统编目中，一个an entry already exists the catlg会报错，并且给出信息。用deleting/uncataloging 第一个数据集去fix 程序，然后去有新的数据集的卷，创建它。Q27) What is S0C7 abend? - GSA27) Caused by invalid data in a numeric field.甚么是S0C7异常终止引起一个数字域里的无效数字Q28) What is a S0C4 error ? - GSA28) Storage violation error - can be due to various reasons. e.g.: READING a file that is not open, invalid address referenced due to subscript error.甚么是S0C4错误存储违反错误由多种原因决定，例，READING是一个美有打开的文件，？Q29) What are SD37, SB37, SE37 abends?A29) All indicate dataset out of space. SD37 - no secondary allocation was specified. SB37 - end of vol. and no further volumes specified. SE37 - Max. of 16 extents already allocated.SD37, SB37, SE37 abends是甚么表示磁盘空间不足SD37没有指定的从分配SB37终止卷，并且没有根多的卷被指定SE37已经分配到最大16 extents（来源：/）Q30) What is S322 abend ?A30) Indicates a time out abend. Your program has taken more CPU time than the default limit for the job class. Could indicate an infinite loop.甚么是S322 abend需要更多的CPU时间程序已经超过了默认的为该作业分配的CPU时间，陷入一个无限循环.?Q31) Why do you want to specify the REGION parameter in a JCL step? - GSA31) To override the REGION defined at the JOB card level. REGION specifies the max region size. REGION=0K or 0M or omitting REGION means no limit will be applied.说明在JCL作业步中的REGION（见书86页）Q32) What does the TIME parameter signify ? What does TIME=1440 mean ?A32) TIME parameter can be used to overcome S322 abends for programs that genuinely need more CPU time. TIME=1440 means no CPU time limit is to be applied to this step.TIME参数的意思是甚么？TIME=1440 表示甚么TIME当程序需要更多的CPU时间时用于克服S322 abendsTIME=1440表示作业的运行没有时间限制，即24小时。Q33) What is COND=EVEN ?A33) Means execute this step even if any of the previous steps, terminated abnormally.COND=EVEN即使先前作业步异常终止，本作业步都要执行Q34) What is COND=ONLY ?A34) Means execute this step only if any of the previous steps, terminated abnormally.COND=ONLY只有先前作业步异常终止，本作业步才执行Q35) How do you check the syntax of a JCL without running it?A35) TYPERUN=SCAN on the JOB card or use JSCAN.如何在一个JCL中检查是否有语法错误在JOB过程中，TYPERUN=SCAN或JSCAN.Q36) What does IEBGENER do?A36) Used to copy one QSAM file to another. Source dataset should be described using SYSUT1 ddname. Destination dataset should be described using SYSUT2. IEBGENR can also do some reformatting of data by supplying control cards via SYSIN.IEBGENER的作用用于copy QSAM文件资源数据集用SYSUT1 ddname.描述，目标数据集SYSUT2描述？IEBGENR也能用控制语句SYSIN来做一些数据的重定格式Q37) How do you send the output of a COBOL program to a member of a PDS?A37) Code the DSN as PDS (member) with a DISP = SHR. The DISP applies to the PDS and not to a specific member.如何给一个PDS的成员输出一个COBOL程序Q38) I have multiple jobs ( JCLs with several JOB cards ) in a member. What happens if I submit it?A38) Multiple jobs are submitted (as many jobs as the number of JOB cards).在一个成员中有几个JOB，如果提交了将会发生甚么？Q39) I have a COBOL program that Accepts some input data. How do you code the JCL statement for this?( How do you code instream data in a JCL? )A39) /SYSIN DD*input datainput data/*有一个接受一些输入数据的COBOL程序，如何为它编一个JCL程序（如何在JCL中编一个流数据）/SYSIN DD*input datainput data/*Q40) Can you code instream data in a PROC ?A40) No.在PROC中的流数据可以编码吗No.Q41) How do you overcome this limitation ?A41) One way is to code SYSIN DD DUMMY in the PROC, and then override this from the JCL with instream data.如何解决这个限制呢在PROC内编写SYSIN DD DUMMY，然后从JCL用流数据覆盖它Q42) How do you run a COBOL batch program from a JCL? How do you run a COBOL/DB2 program?A42) To run a non DB2 program,/STEP001 EXEC PGM=MYPROGTo run a DB2 program,/STEP001 EXEC PGM=IKJEFT01/SYSTSIN DD *DSN SYSTEM(.)RUN PROGRAM(MYPROG)PLAN(.) LIB(.) PARMS()/*如何从JCL运行一个COBOL批处理程序，如何运行一个COBOL/DB2非DB2/STEP001 EXEC PGM=MYPROGDB2/STEP001 EXEC PGM=IKJEFT01/SYSTSIN DD *DSN SYSTEM(.)RUN PROGRAM(MYPROG)PLAN(.) LIB(.) PARMS()/*Q43) What is STEPLIB, JOBLIB? What is it used for? - GSA43) Specifies that the private library (or libraries) specified should be searched before the default system libraries in order to locate a program to be executed. STEPLIB applies only to the particular step, JOBLIB to all steps in the job.甚么是STEPLIB, JOBLIB?如何用他们为作业作业步指定一个私有库（或库），查找时只有在私有库没有的情况下再去搜索系统默认库。STEPLIB的应用仅限于该作业步，而JOBLIB则对于整个作业都有效Q44) What is order of searching of the libraries in a JCL? - GSA44) First any private libraries as specified in the STEPLIB or JOBLIB, then the system libraries such as SYS1.LINKLIB. The system libraries are specified in the link list.在JCL中查找库的顺序是怎样的首先查找私有库，当私有库没有的情况下再去查找系统库。例如SYS1.LINKLIB。系统库在连接表中是指定的Q45) What happens if both JOBLIB and STEPLIB is specified ?A45) JOBLIB is ignored.当一个JCL中既定义了JOBLIB，又定义了STEPLIB，则会怎样JOBLIB被忽略Q46) When you specify mutiple datasets in a JOBLIB or STEPLIB, what factor determines the order? - GSA46) The library with the largest block size should be the first one.当在JOBLIB 或 STEPLIB指定多个数据集时，顺序由甚么因素决定有最大块的LIB为第一个specifyQ47) How to change default PROCLIB?A47) /ABCD JCLLIB ORDER=(ME.MYPROCLIB,SYS1.PROCLIB)如何改变默认的PROCLIB/ABCD JCLLIB ORDER=(ME.MYPROCLIB,SYS1.PROCLIB)Q48) The disp in the JCL is MOD and the program opens the file in OUTPUT mode. What happens ? The DISP in the JCL is SHR and the program opens the file in EXTEND mode. What happens ?A48) Records will be written to end of file (append) when a WRITE is done in both cases.数据集的状态是MOD，在OUTPUT状态下打开文件，将会发生甚么。当为SHR时，在EXTEND状态下打开文件，将会发生甚么。记录将会写在数据集的结尾？Q49) What are the valid DSORG values ?A49) PS - QSAM, PO - Partitioned, IS - ISAMQ50) What are the differences between JES2 & JES3 ?A50) JES3 allocates datasets for all the steps before the job is scheduled. In JES2, allocation of datasets required by a step are done only just before the step executes.JES2 & JES3有甚么区别Scheduled作业时JES3为所有的作也步分配数据集JES2则在作业步执行前为需要的作业步分配数据集Q41) How do you overcome this limitation ?A41) One way is to code SYSIN DD DUMMY in the PROC, and then override this from the JCL with instream data.怎么样克服这个局限？一种方法是在过程中使用SYSIN DD DUMMY语句，然后在JCL中的流内语句中调用他。（来源：/）Q42) How do you run a COBOL batch program from a JCL? How do you run a COBOL/DB2 program?A42) To run a non DB2 program,/STEP001 EXEC PGM=MYPROGTo run a DB2 program,/STEP001 EXEC PGM=IKJEFT01/SYSTSIN DD *DSN SYSTEM(.)RUN PROGRAM(MYPROG)PLAN(.) LIB(.) PARMS()/*Q43) What is STEPLIB, JOBLIB? What is it used for? - GSA43) Specifies that the private library (or libraries) specified should be searched before the default system libraries in order to locate a program to be executed. STEPLIB applies only to the particular step, JOBLIB to all steps in the job.指定一个（或多个）私有的库，为了找到被执行的程序，指定应该在系统默认库之前。STEPLIB只应用于特定的STEP，JOBLIB则应用于JOB里的所有STEP。Q44) What is order of searching of the libraries in a JCL? - GSA44) First any private libraries as specified in the STEPLIB or JOBLIB, then the system libraries such as SYS1.LINKLIB. The system libraries are specified in the link list.在JCL里寻找库的顺序是什么？首先在STEPLIB或JOBLIB指定的库中找，然后再系统库中找，例如SYS1。LINKLIB。系统库在连接表中指定。Q45) What happens if both JOBLIB and STEPLIB is specified ?A45) JOBLIB is ignored.如果在JOBLIB和STEPLIB中都指定了库会怎么处理？JOBLIB语句无效。Q46) When you specify mutiple datasets in a JOBLIB or STEPLIB, what factor determines the order? - GSA46) The library with the largest block size should be the first one.当在JOBLIB或STEPLIB中指定了多个DATASET库，什么因素决定（访问）顺序block size值最大的库应该最先访问。Q47) How to change default PROCLIB?A47) /ABCD JCLLIB ORDER=(ME.MYPROCLIB,SYS1.PROCLIB)怎么改变默认的PROCLIB/ABCD JCLLIB ORDER=(ME.MYPROCLIB,SYS1.PROCLIB)Q48) The disp in the JCL is MOD and the program opens the file in OUTPUT mode. What happens ? The DISP in the JCL is SHR and the program opens the file in EXTEND mode. What happens ?A48) Records will be written to end of file (append) when a WRITE is done in both cases.JCL中DISP为MOD并且程序以