HLASM: V1R6 Language Ref

Beginning of a source moduleYou may provide additional statements for a part by specifying a CATTRstatement with the class name in the name entry and the part name specified asthe operand. No other class attributes may be specified following the first CATTRstatement declaring the class.Parts are automatically assigned a “merge” attribute, meaning that more than oneidentically named part may appear in a class defined in other assemblies orcompilations. The binder will assign the longest length and strictest alignment ofall such identically-named parts, and will merge the machine language textcontributions of each to form the final text belonging to that part. The order of textmerging depends on the sequence of parts processing by the binder.Note: During linking, parts may be arranged in any order, depending on theirpriority attribute. Do not assume any ordering relationship among parts.Location counter settingThe assembler maintains a separate location counter for each section, element, andpart. The location counter setting for the first section starts at 0, except when aninitial section is started with a START instruction that specifies a nonzero locationcounter value. The location values assigned to the instructions and other data in asection, element, or part are, therefore, relative to the location counter setting at thebeginning of that section, element, or part.For executable sections, the location values that appear in the listings depend onthe THREAD option:v If you specify NOTHREAD, the location counter values for each section,element, or part restart at 0, except possibly those associated with a first sectioninitiated by a START instruction with a nonzero address.v If you specify THREAD, location counter values do not restart at 0 for eachsubsequent section, element, or part. They continue, after suitable alignment,from the end of the previous section, element, or part.For reference control sections, the location values that appear in the listings alwaysstart from 0.You can continue a control section, element, or part that has been discontinuedand, thereby, intersperse code sequences from different control sections, elements,or parts. Note that the location values that appear in the listings for suchdiscontiguous sequences are divided into segments that follow from the end of onesegment to the beginning of the subsequent segment.The location values, listed for the next defined control section, element, or part,begin after the last location value assigned to the preceding such item.|On z/VSE, or when you specify the NOGOFF assembler option on z/OS andCMS, the maximum value of the location counter and the maximum length of acontrol section is 2 24 −1, or X'FFFFFF' bytes. If LIST(133) is in force, then thehigh-order byte is shown as zero.60 HLASM: V1R6 Language Ref