HLASM: V1R6 Language Ref

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Sequence symbolsparameter wherever it is used in the macro definition. The value of thesymbolic parameter is a null character string.Example:MACRO&NAME MOVE &TO,&FROM Statement 1&NAME ST 2,SAVEAREA Statement 2L2,&FROMST2,&TOL2,SAVEAREAMEND------------------------------------------------------------------.SYM MOVE FIELDA,FIELDB Statement 3------------------------------------------------------------------+ ST 2,SAVEAREA Statement 4+ L 2,FIELDB+ ST 2,FIELDA+ L 2,SAVEAREAThe symbolic parameter &NAME is used in the name field of the prototypestatement (Statement 1) and the first model statement (Statement 2). In themacro instruction (Statement 3), a sequence symbol (.SYM) corresponds tothe symbolic parameter &NAME. &NAME is not replaced by .SYM and, therefore,the generated statement (Statement 4) does not contain an entry in thename field.LookaheadSymbol attributes are established in either definition mode or lookahead mode.Definition mode occurs whenever a previously undefined symbol is encountered inthe name field of a statement, or in the operand field of an EXTRN or WXTRNstatement during open code processing. Symbols within a macro definition aredefined when the macro is expanded.Lookahead mode is entered:v When the assembler processes a conditional assembly instruction and encountersan attribute reference (other than D' and O') to an ordinary symbol that is notyet defined.v When the assembler encounters a forward AGO or AIF branch in open code to asequence symbol that is not yet defined.Lookahead is a sequential, statement-by-statement, forward scan over the sourcetext.If the attribute reference is made in a macro, forward scan begins with the firstsource statement following the outermost macro instruction. During lookahead theassembler:v Bypasses macro definition and generationv Does not generate object textv Does not perform open-code variable substitutionv Ignores AIF and AGO branch instructionsv Establishes interim data attributes for undefined symbols it encounters inoperand fields of instructions. The data attributes are replaced when a symbol issubsequently encountered in definition mode.336 HLASM: V1R6 Language Ref
LookaheadLookahead mode ends when the desired symbol or sequence symbol is found, orwhen the END statement or end of file is reached. All statements read bylookahead are saved on an internal file, and are fully processed when thelookahead scan ends.If a COPY instruction is encountered during lookahead, it is fully processed at thattime, the assembler copies the statements from the library, scans them, and savesthem on the lookahead file. When lookahead mode has ended any COPYinstructions saved to the lookahead file are ignored, as the statements from thecopy member have already been read and saved to the lookahead file.If a variable symbol is used for the member name of a COPY that is expandedduring lookahead, the value of the variable symbol at the time the COPY isexpanded is used.For purposes of attribute definition, a symbol is considered partially defined if itdepends in any way upon a symbol not yet defined. For example, if the symbol isdefined by a forward EQU that is not yet resolved, that symbol is assigned a typeattribute of U.In this case, it is quite possible that, by the end of the assembly, the type attributehas changed to some other value.Generating END statementsBecause no variable symbol substitution is carried out during lookahead, youshould consider the following effects of using macro, AINSERT or open codesubstitution to generate END statements that separate source modules assembledin one job step (BATCH assembler option). If a symbol is undefined within amodule, lookahead might read statements past the point where the END statementis to be generated. Lookahead stops when:1. It finds the symbol2. It finds an END statement3. It reaches the end of the source input data setLookaheadIn the first two cases, the assembler begins the next module at the statement afterlookahead stopped, which could be after the point where you wanted to generatethe END statement.restrictionsThe assembler analyzes the statements it processes during lookahead, only toestablish attributes of symbols in their name fields.Variable symbols are not replaced. Modifier expressions are evaluated only if allsymbols involved were defined prior to lookahead. Possible multiple orinconsistent definition of the same symbol is not diagnosed during lookaheadbecause conditional assembly may eliminate one (or more) of the definitions.Lookahead does not check undefined operation codes against library macro names.If the name field contains an ordinary symbol and the operation code cannot bematched with one in the current operation code table, then the ordinary symbol isassigned the type attribute of M. If the operation code contains special charactersor is a variable symbol, a type attribute of U is assumed. This may be wrong if theundefined operation code is later substituted with a known operation code or isChapter 9. How to write conditional assembly instructions 337
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High Level Assembler for z/OS & z/V
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Note!Before using this information
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|Open code . . . . . . . . . . . .
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Programming interface informationOr
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IBM High Level Assembler for z/OS &
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Syntax notationFormat▌A▐ ▌B
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Double-byte character set notationx
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Summary of changesxvi HLASM: V1R6 L
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Chapter 1. IntroductionA computer c
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Assembler languagev Macro instructi
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Assembler programProcessingConditio
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Coding made easierCoding made easie
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Chapter 2. Coding and structureThis
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Character setTable 4. Examples usin
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Assembler language coding conventio
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Assembler language structureThe mac
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Assembler language structureMachine
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Assembler language structureConditi
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Mnemonic tags|||||||||For example,
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Terms, literals, and expressions- T
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Terms, literals, and expressionsAss
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Terms, literals, and expressionsUsi
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Terms, literals, and expressions|||
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Terms, literals, and expressionsz/V
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Terms, literals, and expressionsTab
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Terms, literals, and expressions1.
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Terms, literals, and expressions1.
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Terms, literals, and expressions┌
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Terms, literals, and expressionsA-Y
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Chapter 3. Program structures and a
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SourcemoduleA source module is comp
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Beginning of a source modulev The S
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Beginning of a source moduleReferen
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Beginning of a source moduleNote: T
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Beginning of a source moduleClass l
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Beginning of a source modulez/VM an
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AddressingBase Address Definition:
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QualifiedDependentaddressingQualifi
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Addressingz/VM and z/OSWhen you spe
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Addressing..EX_SYM DC V(EXMOD1) Add
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AddressingSee the appendix “Objec
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Part 2. Machine and assembler instr
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Chapter 4. Machine instruction stat
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Input/output operationsThe input or
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Branching with extended mnemonic co
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Statement formatsSymbolic operation
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Operand entriesRegistersYou can spe
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Operand entriesv Explicitly—in a
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Operand entriesImmediateused by the
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Examples of coded machine instructi
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Chapter 5. Assembler instruction st
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*PROCESS statementstatement, follow
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ACONTROL instruction►►NOCOMPAT,
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ACONTROL instructionFLAG(PAGE0)inst
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ACONTROL instruction|||may be fetch
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AINSERT instruction►►sequence_s
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ALIAS instruction||||||The alias_st
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AMODE instructionCATTR instruction
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CATTR instructionRMODE(ANY)The text
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CCW and CCW0 instructionssupport 31
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CEJECT instructionIf number of line
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CNOP instructionAfter the BALR inst
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COPY instructioncopied from either
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CSECT instructionsame section name
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CXD instructionZETA: the resulting
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DC instruction10EBP(7)L2’12’the
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DC instructionTable 17. Length attr
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DC instruction4. Double-byte data i
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DC instructionTable 19. Type codes
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DC instructionYou may omit the modi
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DC instructionfirst constant to be
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DC instructionTable 21. Specifying
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DC instruction—Character constant
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DC instruction—Character constant
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DC instruction—Graphic constantTa
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DC instruction—Fixed-point consta
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DC instruction—Fixed-point consta
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DC instruction—Decimal constantsD
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DC instruction—Address constants|
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DC instruction—Address constantsT
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DC instruction—Offset constantIn
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DC instruction—Hexadecimal floati
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DC instruction—Decimal floating-p
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Syntax of binary, decimal, and hexa
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DC instruction—Binary floating-po
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DROP instructionLabeledDependentIf
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DS instructionv An ordinary symbolv
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DS instructionthe data that follows
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DSECT instructionTo effect referenc
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DXD instructionnominal_valueis the
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END instructionNotes:1. If the END
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EQU instruction||||to the symbol in
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EQU instruction|FPR Register - Floa
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EXITCTL instructionSee the section
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ISEQ instruction►►sequence_symb
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LOCTR instructionA LOCTR name may b
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LTORG instructionAddressingDuplicat
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MNOTE instructionNote: The maximum
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OPSYN instruction||||||v An operati
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ORG instruction||||||||If symbol de
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ORG instructionThat is, the ORG ins
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PRINT instructionPRINT instructionT
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PRINT instructionexceeded the macro
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PUNCH instructionv A pair of single
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REPRO instruction||Notes:1. The ide
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RSECT instructionThe beginning of a
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TITLE instructionv Provides heading
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TITLE instructionIf the TITLE state
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USING instructioninstructions suppo
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USING instructionby means of anothe
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USING instructionLabeled USING inst
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USING instructionDomain of a labele
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USING instructionIf the dependent U
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XATTR instructionXATTR instruction
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XATTR instructionSCOPE(MODULE), abb
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Name entry . . . . . . . . . . . .
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Macro definitionA macro definition
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Macro instructionThe macro instruct
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Where to define a macro in a source
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Prototype statement|||||specified o
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Model statementsEach field or subfi
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Model statementsTable 37. Rules for
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Model statements||v Variable symbol
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Symbolic parametersPositionalKeywor
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Other conditional assembly instruct
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AREAD instruction||If no operand is
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MEXIT instructionThe MEXIT instruct
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System variable symbols1 macro2 get
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&SYSADATA_MEMBER System Variable Sy
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&SYSDATC System Variable SymbolYYYY
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&SYSECT System Variable Symbolv Sta
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&SYSIN_MEMBER System Variable Symbo
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&SYSLIB_DSN System Variable SymbolS
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&SYSLIN_DSN System Variable SymbolE
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&SYSLIST System Variable Symbolposi
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&SYSLOC System Variable Symbolinstr
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&SYSNDX System Variable Symbol1 MAC
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&SYSNDX System Variable SymbolState
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&SYSOPT_RENT System Variable Symbol
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&SYSPRINT_DSN System Variable Symbo
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Page 306 and 307: &SYSSEQF System Variable Symbol1. I
Page 308 and 309: &SYSTEM_ID System Variable SymbolNo
Page 310 and 311: &SYSTERM_VOLUME System Variable Sym
Page 312 and 313: &SYSVER System Variable Symbol294 H
Page 314 and 315: Macro instruction format|name_entry
Page 316 and 317: Macro instruction formatOperandYou
Page 318 and 319: Macro instruction formatAny keyword
Page 320 and 321: Macro instruction formatparameters
Page 322 and 323: Sublists in operandsTable 48. Relat
Page 324 and 325: Values in operandsUnquotedSpecial2.
Page 326 and 327: Values in operands’SPACES ALLOWED
Page 328 and 329: Levels of macro call nestingLevels
Page 330 and 331: Levels of macro call nestingCOMPAT(
Page 332 and 333: Levels of macro call nesting&SYSSEQ
Page 334 and 335: SET symbolsSET symbolsSET symbols a
Page 336 and 337: SET symbolsTable 50. Features of SE
Page 338 and 339: SET symbolspreceding 999999 element
Page 340 and 341: Data attributesTable 51. Data attri
Page 342 and 343: Data attributesThe values of attrib
Page 344 and 345: Data attributesV R-, V-type address
Page 346 and 347: Data attributes|||||||||Notes:1. Or
Page 348 and 349: Data attributesv If the first opera
Page 350 and 351: Data attributesCount attribute (K')
Page 352 and 353: Data attributes||||||defined attrib
Page 356 and 357: LookaheadSequencelater defined by O
Page 358 and 359: GBLA, GBLB, and GBLC instructionsGB
Page 360 and 361: LCLA, LCLB, and LCLC instructions,
Page 362 and 363: Assigning values to SET symbolsLogi
Page 364 and 365: Assigning values to SET symbolsTabl
Page 366 and 367: SETA instructionTable 58. Variable
Page 368 and 369: SETA instructionB2A(’’) has val
Page 370 and 371: SETA instruction|||||||||||||||||||
Page 372 and 373: SETA instructionAfter the following
Page 374 and 375: SETA instruction10. An arithmetic e
Page 376 and 377: SETA instructionarithmetic value
Page 378 and 379: SETB instructionv A logical express
Page 380 and 381: SETB instructionOR Format: Logical-
Page 382 and 383: SETC instructionSETCinstructionThe
Page 384 and 385: SETC instruction|LCLC &C1,&C2LCLC &
Page 386 and 387: Substring notationv When e2 has a v
Page 388 and 389: Substring notation||||ExamplesA2D(0
Page 390 and 391: Substring notationC2X Format: Funct
Page 392 and 393: Substring notationSuppose the SETC
Page 394 and 395: Substring notationX2C(’’) has v
Page 396 and 397: Substring notationFor example, eith
Page 398 and 399: Substring notationStatement 1 assig
Page 400 and 401: SETAF instruction►► variable_sy
Page 402 and 403: AIF instructionsequence_symbolis a
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AIF instructionAIFB—synonym of th
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ACTR instruction►►sequence_symb
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MHELP optionsparameters are dumped
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Assembler instructions and statemen
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Summary of constantsTable 65. Summa
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Macro and conditional assembly lang
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Standard character set code tableHe
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Standard character set code tableHe
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NoticesPURPOSE. Some states do not
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z/VM: CP Planning and Administratio
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ALIAS instruction 108maximum operan
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comment statements (continued)ordin
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GG-type graphic constant 144GBLA in
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macro instructions (continued)opera
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eference constant (R) 154reference
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UUHEADPRINT instruction 206unary op
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