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Virtual Storage Access Method (VSAM) [1] is an IBM direct-access storage device (DASD) file storage access method, first used in the OS/VS1, OS/VS2 Release 1 (SVS) and Release 2 (MVS) operating systems, later used throughout the Multiple Virtual Storage (MVS) architecture and now in z/OS.
IDCAMS probably has the most functionality of all the utility programs, performing many functions, for both VSAM and non-VSAM files. The following example illustrates the use of IDCAMS to copy a dataset to disk. The dataset has 80-byte records, and the system will choose the block size for the output:
An entry-sequenced data set (ESDS) is a type of data set used by IBM's VSAM computer data storage system. [1]: 5 Records are accessed based on their sequential order, that is, the order in which they were written to the file; which means that accessing a particular record involves searching all the records sequentially until it is located, or by using a relative physical address (Relative byte ...
A key-sequenced data set (KSDS) is a type of data set used by IBM's VSAM computer data storage system. [ 1 ] : 5 Each record in a KSDS data file is embedded with a unique key. [ 1 ] : 20 A KSDS consists of two parts, the data component and a separate index file known as the index component which allows the system to physically locate the record ...
Basic, in IBM terminology, indicates a lower-level access method that deals with data sets in terms of physical blocks and does not provide either read-ahead, called anticipatory buffering, or synchronization — that is, the user program has to explicitly wait for completion of each input/output event.
A linear data set (LDS) is a type of data set organization used by IBM's VSAM computer data storage system. [1]: 5 The LDS has a control interval size of 4096 bytes to 32768 bytes [2] in increments of 4096.
This numbering is generated by Natural during program creation. Line numbers used by the compiler and editors, and can have important logical functions in the programs. Comments can be included in two ways: Full-line comments are identified by a "*" or "**" prefix. Annotated code lines have a "/*" - everything to its right is a comment. Examples:
Examples of this are the x86 calling conventions. Adhering to an ABI (which may or may not be officially standardized) is usually the job of a compiler, operating system, or library author. However, an application programmer may have to deal with an ABI directly when writing a program in a mix of programming languages, or even compiling a ...