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The Sort/Merge utility is a mainframe program to sort records in a file into a specified order, merge pre-sorted files into a sorted file, or copy selected records. Internally, these utilities use one or more of the standard sorting algorithms , often with proprietary fine-tuned code.
The operation of SORT is directed by control statements, which are largely compatible among various IBM and third-party sort programs. The SORT or MERGE statement defines the sort keys— the fields on which the data is to be sorted or merged. This statement identifies the position, length, and data type of each key.
External sorting algorithms generally fall into two types, distribution sorting, which resembles quicksort, and external merge sort, which resembles merge sort. External merge sort typically uses a hybrid sort-merge strategy. In the sorting phase, chunks of data small enough to fit in main memory are read, sorted, and written out to a temporary ...
As it is an assembly language, BAL uses the native instruction set of the IBM mainframe architecture on which it runs, System/360, just as the successors to BAL use the native instruction sets of the IBM mainframe architectures on which they run, including System/360, System/370, System/370-XA, ESA/370, ESA/390, and z/Architecture.
The z/OS operating system (MVS' most recent descendant) also has native support to execute POSIX and Single UNIX Specification applications. The support began with MVS/SP V4R3, and IBM has obtained UNIX 95 certification for z/OS V1R2 and later. [5] The system is typically used in business and banking, and applications are often written in COBOL.
Samplesort is a sorting algorithm that is a divide and conquer algorithm often used in parallel processing systems. [1] Conventional divide and conquer sorting algorithms partitions the array into sub-intervals or buckets. The buckets are then sorted individually and then concatenated together.
The pairwise sorting network is very similar to the Batcher odd-even mergesort, but differs in the structure of operations. While Batcher repeatedly divides, sorts and merges increasingly longer subsequences, the pairwise method does all the subdivision first, then does all the merging at the end in the reverse sequence.
In IBM mainframe operating systems OS/360 and its successors, a Unit Control Block (UCB) is a memory structure, or a control block, that describes any single input/output peripheral device (unit), or an exposure (alias), to the operating system.