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Custom programs can access VSAM datasets through Data Definition (DD) statements in Job Control Language (JCL), via dynamic allocation or in online regions such as in Customer Information Control System (CICS). Both IMS/DB [citation needed] and Db2 [2]: 41 [6] are implemented on top of VSAM and use its underlying data structures.
IDCAMS ("Access Method Services") generates and modifies Virtual Storage Access Method (VSAM) and Non-VSAM datasets. IDCAMS was introduced along with VSAM in OS/VS; the "Access Method" reference derives from the initial "VSAM replaces all other access methods" mindset of OS/VS. IDCAMS probably has the most functionality of all the utility ...
Job Control Language (JCL) is a scripting language used on IBM mainframe operating systems to instruct the system on how to run a batch job or start a subsystem. [1] The purpose of JCL is to say which programs to run, using which files or devices [2] for input or output, and at times to also indicate under what conditions to skip a step.
JCL is used to define jobs to both JES2 and JES3, but small changes usually need to be made to the JCL to get a job written for one JES to run on the other. A common issue was that JES3 checked that all datasets listed in the JCL existed before execution or that there was a prior step where the dataset was defined as NEW,CATLG.
By design, programs written for MVS run on z/OS without modification. At first IBM described MVS as simply a new release of OS/VS2 , but it is, in fact a major rewrite. OS/VS2 release 1 is an upgrade of OS/360 MVT that retained most of the original code and, like MVT, is mainly written in assembly language .
POCO—Plain Old Class Object; POID—Persistent Object Identifier; POJO—Plain Old Java Object; POP—Point of Presence; POP3—Post Office Protocol v3; POSIX—Portable Operating System Interface, formerly IEEE-IX; POST—Power-On Self Test; PPC—PowerPC; PPI—Pixels Per Inch; PPM—Pages Per Minute; PPP—Point-to-Point Protocol; PPPoA ...
In the context of IBM mainframe computers in the S/360 line, a data set (IBM preferred) or dataset is a computer file having a record organization.Use of this term began with, e.g., DOS/360, OS/360, and is still used by their successors, including the current z/OS.
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.