IBM 5280 Distributed Data System - Index of

Altocate a Data Set (AllOC)Source:Object:II Data set number: The number (hex 1-F) of data set to allocate.f.I Parameters' address: The address of the binary register that contains theaddress of the allocate parameters. The binary register must be preceded bytwo commas in the source instruction.This instruction is always executed in nonoverlapped mode. For a printer, thisinstruction is executed as an open instruction. For diskette, when the ALLOCoperation is executed the data set is allocated in the physical space followingthe last valid data set existing on the diskette, provided sufficient extent and labelspace exists. A data set cannot be allocated between existing data sets and alwaysorigrnates on a physical track/sector boundary.The data set HDR1 label is placed in the first deleted HDR1 label space. If thereare no deleted HDR 1 label spaces, the allocation cannot take place, and an externalstatus (3229) is presented. The HDR1 information is taken from the data set lOBand from the parameter string in storage. The binary register (BRn) in the ALLOCinstruction contains the address of the fifth byte of the parameter string. Theformat of the parameter string is as follows:ByteMeaningData set exchange type. A hex number that corresponds to theappropriate exchange type:00 = Basic exchange01 = H exchange02 = I exch8flge (this is the type normally used)03 = E exchange, unblocked and unspanned04 = E exchange, blocked and unspanned05 = E exchange, blocked and-spanned2-4 The number of logical records to allocate. Hex 000000 allocatesthe maximum number of records that can be placed on the remainingdiskette space.5 The first of up to 14 characters of an optional owner identification,required for allocating pn a secure diskette. The address stored inthe binary register always points to this byte. If the owner identificationis omitted, the address points to the end blank.Object Code Instruction Format 189