HLASM: V1R6 Language Ref

System variable symbols1 macro2 getlocalsys3 .* Define globals for values of interest4 Gblc &clock,&location,&dsname,&nest5 Gbla &nesta6 .* now update the globals from within the macro7 &clock setc ’&sysclock’8 &location setc ’&sysloc’9 &dsname setc ’&sysin_dsn’10 &nest setc ’&sysnest’11 &nesta seta &sysnest12 mend000000 00000 00020 14 r csect15 *16 * define globals in opencode17 *18 Gblc &clock,&location,&dsname,&nest19 Gbla &nesta20 *21 * invoke macro to update the global values22 *23 getlocalsys24 *25 * now use the updated values26 *27 dc c’&clock’000000 F2F0F0F460F0F660 + dc c’2008-07-11 17:48:42.914829’28 dc c’&nest’00001A F1 + dc c’1’29 dc f’&nesta’00001B 0000001C 00000001 + dc f’1’000000 31 end rFigure 27. Exposing the value of a local scope variable to open codeUses, Values and PropertiesSystem variable symbols have many uses, including:v Helping to control conditional assembliesv Capturing environmental data for inclusion in the generated object codev Providing program debugging dataRefer to Appendix C, “Macro and conditional assembly languagesummary,” on page 405 for a summary of the values and properties thatcan be assigned to system variable symbols.&SYSADATA_DSN System Variable SymbolUse &SYSADATA_DSN in a macro definition to obtain the name of the data set towhich the assembler is writing the associated data.The local-scope system variable symbol &SYSADATA_DSN is assigned a read-onlyvalue each time a macro definition is called.z/OSWhen the assembler runs on the z/OS operating systems, the value of thecharacter string assigned to &SYSADATA_DSN is always the value stored in theJFCB for SYSADATA. If SYSADATA is allocated to DUMMY, or a NULLFILE, thevalue in &SYSADATA_DSN is NULLFILE.For example, &SYSADATA_DSN might be assigned a value such as:IBMAPC.SYSADATA260 HLASM: V1R6 Language Ref