mainframe面试试题总结黄金版

- 1 把 DB2 连接到 COBOL 有几个编译步骤；（SZ） DB2 pre-compiler (if embedded SQL used), CICS translator (if CICS program), COBOL compiler, Link editor, binding the DBRMs using the package or plan. 2VSAM 与 DB2 的区别； （SZ ） 一是 VSAM 使用前需要事先在环境部做文件定义和在数据部申明文件数据描述，DB2 不需 要； 二是读写 VSAM 文件时使用的都是 CICS COMMANDS，而 DB2 的使用是嵌入的 SQL 语 句； 三是 VSAM 也有索引的定义和使用，但是不如 DB2 使用的广泛，DB2 有唯一索引，外键， 主键等保证查询快速； 四是 VSAM 查询每次读文件都是对一行数据，而 DB2 可以查询任意字段； 五是在线交易中使用 VSAM 前，需要在 CICS 中事先用命令 CICS CEMT SET FILE（XXXX ） OPEN 打开文件，而 DB2 可直接操作； 3如何保证系统的安全；（SZ） 一是有大型机系统自己的安全系统； 二是有授权管理系统管理所有用户群和资源； 4什么是系统前台和后台，什么是系统架构；（SZ） 前台是 CICS，后台是 MVS。 系统由销售，生产，财务，技术质量，出货和授权管理等 6 大子系统组成，授权管理贯串 系统始末。系统由在线维护程序，在线后台程序，批次维护程序，批次报表程序等类型交 相使用，保证系统的最大优化和高性能。由 OS390 大型服务器，终端和武钢特有的网络协 议保证产销系统健康稳定运行。 5作为一名 LEADER，怎么控制项目工程进度；（SZ ） 一是统筹的使用时间和人力资源； 二是科学的人力绩效制度； 三是科学的工程管理制度； 四是 LEADER 良好的行政执行力和员工的团队合作精神； 6在 DD 语句中，DISP 参数的含义；（DL） DISP=（SUBPARAMETER1 ，SUBPARAMETER2，SUBPARAMETER3 ） SUBPARAMETER1：Status subparameter. (NEW/OLD/SHR/MOD) NEW indicates that a new data set is to be created in this step. 创建一个新的数据集。 OLD indicates that the data set exists before this step and that this step requires exclusive (unshared) use of the data set. 是一个旧的数据集，在同一个时间只允许一个人使用，其他的人等待。 SHR indicates that the data set exists before this step and that other jobs can share it, that is, use it at the same time. 已经存在的数据集，允许多个人同时使用的数据集 MOD indicates one of the following: 1, The data set exists and records are to be added to the end of it. The dataset must be sequential; 2, A new data set is to be created. In either case, MOD specifies exclusive (unshared) use of the data set. SUBPARAMETER2：Normal termination disposition subparameter. (DELETE/KEEP/PASS/CATLG/UNCATLG) DELETE indicates that the data set is no longer needed and is deleted if this step terminates normally. KEEP indicates that the data set is to be kept on the volume if this step terminates normally. PASS indicates that the data set is to be passed for use by a subsequent step in the same job. CATLG indicates that, if the step terminates normally, the system is to place an entry pointing to the data set in the system or user catalog. Note that the data set is kept. UNCATLG indicates that, if the step terminates normally, the system is to delete (1) the entry pointing to the data set in the system or user catalog and (2) unneeded indexes, except for the highest level entry. Note that the data set is kept. SUBPARAMETER3：Abnormal termination disposition subparameter. (DELETE/KEEP/CATLG/UNCATLG) DELETE indicates that the data sets space on the volume is to be released if this step terminates abnormally. The space can be used for other data sets; the data set is not erased from the space. KEEP indicates that the data set is to be kept on the volume if this step terminates abnormally. CATLG indicates that, if the step terminates abnormally, the system is to place an entry pointing to the data set in the system or user catalog. Note that the data set is kept. UNCATLG indicates that, if the step terminates abnormally, the system is to delete (1) the entry pointing to the data set in the system or user catalog and (2) unneeded indexes, except for the highest level entry. Note that the data set is kept. 7在 DD 语句中，DCB 参数的含义；（DL ） Use the DCB parameter to complete during execution the data set information in the data control block (DCB). DSORG specifies the organization of the dataset, sequential or partitioned. RECFM specifies the record format of the dataset, FB, F, V, VB or other. DSNTYPE specifies the type of the dataset, PS, PO, or LIBRARY. BLKSIZE specifies the block size of the dataset, can be default. LRECL specifies the record length of the dataset. 8在 JCL 中，PROCEDURE 的类型（IN-STREAM PROCEDURE，CATALOGED PROCEDURE）以及它们的用法；（DL ） For a cataloged procedure: /name PROC parameter comments /name PROC For an in-stream procedure: /name PROC parameter comments /name PROC Elwen Zhao Page 3 8/15/2018 A name is required on a PROC statement in an in-stream procedure and is optional on a PROC statement in a cataloged procedure. A PROC statement must be the first statement in a procedure. An in-stream procedure must appear in the same job before the EXEC statement that calls it. A cataloged procedure appears in a procedure library, usually SYS1.PROCLIB. 9在 DB2 中，什么情况会产生 SQLCODE= -811；（DL） Execution of an embedded SELECT statement or a sub select in the SET clause of an UPDATE statement has resulted in a result table that contains more than one row. IF embedded SELECT statement causes this problem, defining a CURSOR is recommended. 10在 DB2 中，TABLESPACE 有几种类型(简单表空间，分段表空间，分区表空间，LOB 表空间） ；（DL） 使用表空间的一个明显的好处是能够把数据合理的分布存储在不同的磁盘上或者存储在磁 盘的不同位置上，有助于提高数据存取的效率。DB2 的表空间按管理方式分为两种：系统 管理空间（System Management Space，SMS）和数据库管理空间（Database Management Space，DMS）。按类型分为：规则表空间、大对象表空间、系统临时表空间、用户临时表 空间。 DB2 共有 4 类表空间：简单表空间(simple tablespace)，分段表空间 (segmented tablespace)， 分区表空间(partitioned tablespace)，LOB 表空间(lob tablespace)。 11在 COBOL 中，如何在程序之间进行通信，通信方式有几种；（DL） A, 通常使用通信变量和宏变量 DFHCOMMAREA；由 DFHCOMMAREA 执行传递的功能； 12VSAM 数据集有几种类别（KSDS，ESDS，RRDS） ；（ DL） ESDS： Entry Sequential Data Set; 顺序数据集； 特点是：A，记录只能增加在文件尾部； B，记录可被修改但长度不能被改变，记录不能被 删除；C 能根据相对寻址的方式进行操作。 RRDS：Relative Record Data Set; 相对记录数据集； 特点是：A，在数据集中包含许多小的数据块，这些可能有数据或为空；B，记录可能是固 定的或可变的；C，肯顺序或直接的存取，根据相对的记录数方式操作。 KSDS：Key Sequential Data Set; 索引数据集； 特别是：A，记录能进行顺序或直接的读写； B，记录能被新增、修改、删除无限制，记录 由索引方式来组织；C，按键值的方式进行操作。 13在 CICS 中，有几种 CICS COMPONENT（PCT，PPT，FCT ，TCT） ；（DL） PCT Program Control Table - defines each transaction, containing a list of valid transaction identifiers (transid) where each transaction is paired with its matching program; PPT Program Processing Table - contains a list of valid program names and maps and whether a current version is in the CICS region or needs to be brought in as a new copy; FCT File Control Table - contains a list of files known to CICS, the dataset name and status (closed/open, enabled/disabled); TCT Terminal Control Table - a list of the terminals known to CICS. 14在 CICS 中，有几种定义 TRANSACTION 的方式 （CEDA，SPI，DFHCSDUUP，CICSPlex SM Business Application Services） ；（DL） A, Using the CEDA transaction; B, Using the DFHCSDUP utility; C, Using the SPI(System Programming Interface); D, Using CICSPlex System Manager Business Application Service. 15如何控制程序从一个 TRANSACTION 跳转到另一个 TRANSACTION；（DL） 由一个交易跳转到另一个交易有 3 种调用方式，分别是 XCTL，LINK 和 CALL。指明一个 已在 PCT 中存在的交易或者在 PPT 中已存在的程序，即可准确跳转。 16JCL Utility:拷贝数据集 （IEBGENER ，IEBCOPY ） ；（ CD） IEBGERNER is used to create, copy or print sequential datasets; copy records from a sequential dataset or convert a dataset from sequential organization to a partitioned organization. IEBCOPY is used to copy, compress, merge partitioned datasets or PDSEs; add RLD(reload) count information to load modules; select or exclude specified members in a copy operation; rename or replace selected members of partitioned datasets or PDSEs. 17数据集的比较：IEBCOMPR, SuperC, 要求会在界面环境下使用；（ CD） IEBCOMPR is a data set utility used to compare two sequential data sets, two partitioned data sets or two PDSEs at the logical record level to verify a backup copy. Fixed, variable, or undefined records from blocked or unblocked data sets or members can also be compared. However, you should not use IEBCOMPR to compare load modules. SuperC: Compare and report on differences between data set contents. The SuperC utility (option 3.12) is a dialog that uses the SuperC program to compare data sets of unlimited size and record length at the file, line, word, or byte level. 18使用 SORT Utility 如何去掉数据集中的重复记录；（CD） DFSORT 是IBM 的Data Facility 家族的一员,用来对数据集进行排序、拷贝和合并。 使用 SORT Utility 去掉两个文件的重复记录的程序： 000100 /SORT JOB ,CLASS=A,MSGCLASS=A,NOTIFY= 72:LENGTH; CH: 类型; A: ASENDING * 001200 /*SUM 参数： 73:POSITION; 8:LENGTH; ZD:FORMAT * 001300 /* 注意 :SORT 的 FIELDS 与 SUM 的 FIELDS 不能重叠 * 001300 /*SUM 的 FIELDS 的起始位置应至少为文件中最长的记录的长度 1，记录 * Elwen Zhao Page 5 8/15/2018 001300 /*长度以 PCCOMM 软件屏幕的右下角为准。 * 001400 /* 001500 /SYSIN DD * 001600 SORT FIELDS=(1,72,CH,A) 001700 SUM FIELDS=(73,8,ZD) 19JCL 作业中使用 SQL 语句操作数据库；（ CD） The UNLOAD utility can unload data from one or more source objects to one or more BSAM sequential data sets in external format. The source objects can be DB2 table spaces or DB2 image copy data sets. The UNLOAD utility does not use indexes to access the source table(s). The utility scans the table space or partition(s) directly. 20DISP 各参数的意思；（CD） 参照第 6 题答案。 21GDG；（CD） GDG stands for generation data group. It is a dataset with versions that can be referenced absolutely or relatively. It is defined by an IDCAMS define generation data group execution. GDG - group of dataset that are logically or chronologically related, referred by name and a relative generation number - an integer which identifies the generation of a dataset and is coded in parentheses after dataset name. Absolute GDG name - GxxxxVyy, where xxxx-absolute gen. number, yy-version number. Can be sequential, direct, partitioned. (VSAM - no). Must always be cataloged. Advantage - all datasets have the same name and system keeps track of adding new and retaining previous generations and deleting oldest successive generation. To create a GDG we create a GDG index in the system catalog with IDCAMS utility and then a model (prototype, DSCB) on the same volume to supply DCB information. Empty - when limit is reached all members are removed from the index, otherwise-only oldest. Scratch-removed members are uncataloged Kinds of Utilities：Online utilities can run when DB2 start, such as REORG, RUNSTATS；Offline utilities need DB2 stop, such as DSNJ003, DSNJLOGP. Utility COPY: Backup tablespace; Full imagecopy/incremental imagecopy; SYSIBM.SYSCOPY; Utility RUNSTATS: Collect the newest information of tablespace,;When bind the program, these information is used to decide the access path; Utility REORG: Recluster the data; Restore freespace; After modify PRIQTY、SECQTY; Reclaim space for DROPed tables in simple TS; Rebuild defined indexes; 25COBOL 程序处理流程（在线） ；（CD） A，在 SDF II 中设计 MAP； B，建立相关数据库和定义相关文件，并在程序中的环境部和数据部作相关的申明和定义； C，程序部中，对程序进行异常处理； D，程序部中，对 MAP 进行初始化处理； E，程序部中，实现 ACTION KEYS 各功能键的功能； F，程序部中，RECEIVE MAP； G，程序部中，此是程序的主体部分：操作处理详细代码； H，程序部中，SEND MAP； I，在 RCT 中，使用 CICS 命令对 MAP，MAPSET，PROGRAM，TRANSACTION，FILE 等资源进行定义并安装； 26Tablespace；（CD） DB2 共有 4 类表空间：简单表空间(simple tablespace)，分段表空间 (segmented tablespace)， 分区表空间(partitioned tablespace)，LOB 表空间(lob tablespace)。 修改表空间： ALTER TABLESPACE DSN8D71A.DSN8S71D BUFFERPOOL BP2 LOCKSIZE PAGE; (BP2 is the buffer pool associated with the table space. PAGE is the level at which locking is to take space.) 创建表空间： CREATE TABLESPACE DSN8S71D IN DSN8D71A USING STOGROUP DSN8G710 PRIQTY 52 SECQTY 20 ERASE NO LOCKSIZE PAGE BUFFERPOOL BP1 CLOSE YES; (Let DB2 define the data sets, using storage group DSN8G710. The primary space allocation is 52 kilobytes; the secondary, 20 kilobytes. The data sets need not be erased before they are deleted. Locking on tables in the space is to take place at the page level. Associate the table space with buffer pool BP1. The data sets can be closed when no one is using the table space. ) 27在写 SQL 语句时是否考虑了 SQL 语句的性能？（性能优化问题） （CD） 还有就是至少要熟悉一个项目，用中文和英语都能够进行描述；（CD） 遵守以下几个规则可大大提高 SQL 语句的性能和降低语句执行时的 CPU 资源消耗： A， 尽量在每张表中定义主键和唯一索引； Elwen Zhao Page 7 8/15/2018 B， 尽量不使用 LIKE 关键字和通配符% ， _； C， 尽量不在 WHERE 子句中使用算术表达式； D， 查询时，尽量不使用*代替所有表字段，将所有需要查询的字段一一列举； E， 定义游标时，尽量加上 WITH HOLD 和 WITH UR 或 WITH RR 等语句避免多个用户同 时访问表时影响速度； F， 定义游标时，尽量加上 OPTIMIZE FOR N ROWS 等系统优化语句； G， 尽量不使用连接（JOIN） ，联合（UNION）等涉及到 2 个表以上的谓词； 项目描述（略） 。 28Types of projects；（DL） 钢铁制造业的资讯系统，包括人力资源，生产，销售，财务，技术管理等主科目系统； 29Work role；（DL ） 大型机开发和维护工程师，负责资讯系统新旧系统（详细介绍产品质量与技术管理系统） 的转换开发，负责新资讯系统（详细介绍产品质量与技术管理系统）的运营维护； 30How to control the performance of database（DL） 参考 27 题答案 31Which DB2 utilities do you know? What about BACKUP? （DL） a) LOAD，UNLOAD；可参考 24 题答案； b) 使用 COPY Utility 可以备份数据库； /SYSIN DD * COPY TABLESPACE DBFINA.TSAA08 COPYDDN SYSCOP01 DEVT TAPE FULL YES 32How to compile COBOL with DB2（DL ） a) 预编译作业步：检查 SQL 语句并产生数据库请求模块；检查主机变量； b) COBOL 作业步：检查 COBOL 程序的语法及语义； c) 连接作业步：检查 CICS 命令和语法，产生可执行模块； d) 绑定作业步：BIND PLAN/PACKAGE，绑定 COBOL 和 DB2； 33The function of DB2 table（DL ） often use DB2 to create tables, select data form tables, insert rows of records into tables; 34The usage of CICS（DL） CICS provides the following support: Data Communications An interface between the terminal and printers with CICS via a telecommunication access method (TCAM or VTAM). Multi Region Operation(MRO), through which more than one CICS region of a system can communicate Intersystem Communication (ISC), through which one CICS region of a system can communicate with other CICS regions in other systems Application Programming Interfaces with programming languages such as COBOL and Assembler Command level translator An Execution Diagnostic Facility (EDF) A Command Interpreter Data Handling An interface with database access methods such as DB2, DL/1, and VSAM An interface with error checking and reporting facilities Terminology: CICS has its own language. Some of the language abbreviations of CICS are: SIT System Initialization Table PCT Program Control Table PPT Program Processing Table TCT Terminal Control Table FCT File Control Table TCP Terminal Control Program TCTUA Terminal Control Terminal User Area DCT Destination Control Table TDQ Transient Data Queue EIP Execution Interface Program FCP File Control Program ICP Interval Control Program KCT Task Control Program PCP Program Control Program SCP Storage Control Program TCA Task Control Area TCTTE Terminal Control Table Terminal Entry TSQ Temporary Storage Queue TWA Task Work Area AID Attention Identifier CWA Common Work Area MRO Multi Region Operation QID Queue Identifier 35What is the Level-77 data-item?（SZ ） Elementary level item. It cannot be subdivisions of other items (cannot be qualified), nor can they be subdivided themselves. 36What is COMP-3 ? （SZ ） COMP-3 is packed decimal format. Sign is stored in the last nibble. For example if your number is +100, it stores hex 0C in the last byte, hex 1C if your number is 101, hex 2C if your number is 102, hex 1D if the number is -101, hex 2D if the number is -102 etc. S9(7) COMP-3 field will take 4 bytes. Sign is stored as hex value in the last nibble. General formula is INT(n/2) + 1), where n=7 in this example. Elwen Zhao Page 9 8/15/2018 37Abend system code S0C7（SZ ） S0C7-may be due to: 1. Numeric operation on non-numeric data; 2. Un-initialize working-storage; 3. Coding past the maximum allowed sub script. 38What is the difference between XCTL and LINK ? （SZ） The XCTL command transfer control to an application program at the same logical level (do not expect to control back), while the LINK command passes control to an application program at the next logical level and expects control back. 39How to operate the file in a batch program? （SZ ） 可使用 READ, REWRITE, WRITE, DELETE，START 分别对文件进行读，重写，写，删除， 定位；对文件操作可以是顺序的也可以按照主键值进行读写；对文件读写之前，需先打开 文件，使用完毕需关闭文件； 40What is the process of one online program ? （SZ） A, initiation; B, handle the abend condition; C, process the functions D, receive MAP; E, process the main procedures; F, send MAP; 41What is the difference between TDQ and TSQ ? （SZ） Temporary Storage Queue names are dynamically defined in the application program, while TDQs must first be defined in the DCT (Destination Control Table). When a TDQ contains certain amount of records (Trigger level), a CICS transaction can be started automatically. This does not happen when using a TSQ. TDQ(extra partition) may be used by batch application; TSQ cannot be accessed in batch. The Transient Data Queue is actually a QSAM file. You may update an existing item in a TSQ. A record in a TDQ cannot be updated. Records in TSQ can be read randomly. The TDQ can be read only sequentially. Records in Temporary Storage can be read more than once, while records stored in Temporary Data Queues cannot. With TDQs it is “one read” only. 42What is the utility of SORT? （SZ） DFSORT 是IBM 的Data Facility 家族的一员,用来对数据集进行排序、拷贝和合并。 控制选项: SORT:指定对数据集进行排序操作；MERGE:指定对数据集进行合并操作；COPY:指定对数据 集进行拷贝操作； FIELDS:指定排序键值的信息,格式为 FIELDS=(起始位置,长度,升降序,起始位置,长度,升降序),FORMAT=数据类型 (起始位置,长度,数据格式,升降序,起始位置,长度,数据格式,升降序) 其中位置和长度都是以字节为单位,顺序可选的有A:升序,D:降序,E:使用用户出口例程定序; FORMAT=指定键字的类型,可选项有CH:字符类型,PD:压缩十进制型,BI:二进制型,AC:ASCII 码型。 43 How to transfer parameters by JCL? （SZ） Use the PARM parameter to pass variable information to the processing program executed by this job step. To use the information, the processing program must contain instructions to retrieve the information. When you code more than one subparameter, separate the subparameters by commas and enclose the subparameters in parentheses or apostrophes. For example, PARM=(P1,123,MT5) or PARM=P1,123,MT5. PARM 用于向本作业步执行的程序传递变量信息。该程序必须有相应的指令接收这些信息，并 使用它们。 格式： PARM.过程步名= 子参数 PARM.过程步名=( 子参数, 子参数) PARM.过程步名=(子参数 , 子参数) PARM.过程步名=子参数, 子参数 包括所有的逗号、撇号以及括号在内，所有子参数的总长度不得超过 100 个字符。当某 子参数中含有特殊字符或空格时，可以将该子参数用撇号括起来，在其它子参数一起用括 号 括起来，或将所有在参数用撇号括起来。 子参数：包含传递给程序的变量信息。 例 1 /RUN3 EXEC PGM=APG22,PARM=P1,123,P2=5 在本例中，系统将参数 P1、123 及 P2=5 传递给程序 APG22。 例 2 / STP6 EXEC PROC=ASFCLG,PARM.LKED=(MAP,LET) 在本例中系统将 MAP、LET 传递到过程 ASFCLG 中名为 LKED 的过程步。 44Basic commands of DB2（ SZ） The DISPLAY command can return the following environmental data: DATABASE info, RLIMIT info, THREAD info, TRACE info, and UTILITY info. The RECOVER BSDS command can establish the Boot Strap Data Set after an I/O failure. The START RLIMIT command can reset after it has been stopped by DB2. Using the DISPLAY DATABASE command can determine the status of a tablespace. 45How to use the cursor? （SZ） Step 1: Declare the cursor; Step 2: Open the cursor; Step 3: Specify what to do at end-of-da