Abstract: If a real memory-backed demand paging virtual store is used as a work device in an external sort, then data movements and processing time are substantially less than that for processing the same external sort in either an internal (real) memory or DASD serving as the work device. Also, reblocking of generated partial sort strings during the sort phase and of the totally ordered string during the merge phase is avoided. The optimum ratio of internal (real) memory backing to the virtual store lies between 30-80 percent. Page faulting is reducible as a consequence of the fact that in the external sorting using the virtual store as a work device, a data element need only be referenced twice.

Abstract: A method and means for extending the collation functions of a sorting program (SORT) enable the program to permute, combine, or filter input records having collating characteristics that are not recognized by the SORT program. The extension includes provision of an extended function support program (EFS) that can be invoked by and concurrently executed with the sorting program. The EFS program is provided with a modality for modifying control statements received by the SORT program but executable only against records having the non-recognized collating characteristics. The EFS program modifies such control statements to a form executable by the SORT program. The EFS program also is provided with the capability of modifying the collating characteristic fields of records which are to be processed by the SORT program, the modification resulting in the provision of the records of counterpart collating characteristics recognized by the SORT program.

Abstract: A program controlled digital computer is operated according to a utility program, such as a sort program which manages input/output directly (using very efficient execute channel programs (EXCP) or basic sequential access method (BSAM) facilities of the operating system), but in such a way as to provide to the caller (that is, the application program) the status and error information that is required. This is accomplished by defining an interface between the caller and sort enabling the caller to specify the names of the input and output data sets, the locations of routines to be executed for input and output, the locations of routines to be executed upon exit from input/output routines, and data areas for status information.