HP 3000 Manuals HP 3000 Manuals
Overview Using this COBOL system, you can lock either a single record, a group of records, or a whole file. When data is locked by one operator, no other operator can delete or change that data. Details on how to lock data are given in the section "Including Multi-User Syntax in Your Program" . If the operator locks the whole file (called an exclusive lock), no other operator can access that file at all. If the operator is locking records (either single record locks or multiple record locks) the file is shareable with other operators. The other operators may also be locking records in the same file. Each operator can be locking a single record or multiple records. Any operator can access any data that is not locked by another operator. The operator can open several data files at the same time, and can specify locking for each data file that is opened. However, the operator is allowed only one type of locking for each file - that is, locking of the whole file, locking of a single record, or locking of multiple records. When you do not explicitly specify locking in your program, the default locking is used. The default locking in this COBOL system is for files opened I-O, OUTPUT or EXTEND to become EXCLUSIVE. That is, the whole file is locked by your program. If, however, your program opens the file for INPUT, the file becomes shareable, and your program cannot hold record locks on the file. Other operators can open the file for INPUT. This default locking is used for each file that your program opens when no LOCK MODE syntax is included in your program. You can change the default locking to shareable for files of all organizations opened INPUT or I-O, and also for sequential files opened EXTEND with the AUTOLOCK or FILESHARE compiler option. This feature is included only for compatibility with previous products. We recommend that in new programs you should explicitly specify the required lock mode in the SELECT statement.