Systems Reference LibraryIBM System/360 Operating SystemSystem Programmer's GuideThis publication describes:File No. S360-20Form C28- 6550- 2 OS• How to maintain the data set cataloging facility ofthe Operating System and the volume-table-of-contents (VTOC) of a direct-access volume.• How to modify or extend capabilities of the Operat-ing System in the areas of job and job-stepaccounting~ processing of magnetic tape labels, andSVC routines.• How to implement the data set protection feature ofthe Operating System.• How to write a shift initiator program for use whenthe multiprogramming with a fixed number of tasks(MFT) option is incorporated in the OperatingSystem.• How to use the EXCP (Execute a Channel Program) andXDAP (Execute a Direct-Access Program) macro-instructions, the Resident Access-Method and BLDLTable options, and the tracing routine.Also included are descriptions of system macro-instructions used in modifying the control program.