HLASM: V1R6 Language Ref

CNOP instructionAfter the BALR instruction is generated, the location counter is at a doublewordboundary, thereby ensuring that the CCW instruction immediately follows thebranch and link instruction.The CNOP instruction forces the alignment of the location counter to a halfword,fullword, doubleword or quadword boundary. It does not affect the locationcounter if the counter is already correctly aligned. If the specified alignmentrequires the location counter to be incremented, no-operation instructions aregenerated to fill the skipped bytes. Any single byte skipped to achieve alignmentto the first no-operation instruction is filled with zeros, even if the preceding bytecontains no machine language object code. A length attribute reference to the nameof a CNOP instruction is always invalid. Message ASMA042E will be issued, and adefault value of 1 is assigned.COMinstructionThe COM instruction identifies the beginning or continuation of a common controlsection.►►symbolCOM►◄symbolis one of the following:v An ordinary symbolv A variable symbol that has been assigned a character string with a value thatis valid for an ordinary symbolv A sequence symbolThe COM instruction can be used anywhere in a source module after the ICTLinstruction.If symbol denotes an ordinary symbol, the ordinary symbol identifies the commoncontrol section. If several COM instructions within a source module have the samesymbol in the name field, the first occurrence initiates the common section and therest indicate the continuation of the common section. The ordinary symbol denotedby symbol represents the address of the first byte in the common section, and has alength attribute value of 1.If symbol is not specified, or if name is a sequence symbol, the COM instructioninitiates, or indicates the continuation of, the unnamed common section.See “CSECT instruction” on page 122 for a discussion on the interaction betweenCOM and the GOFF assembler option.The location counter for a common section is always set to an initial value of 0.However, when an interrupted common control section is continued using theCOM instruction, the location counter last specified in that control section iscontinued.Chapter 5. Assembler instruction statements 119