Differences

GDDM V3R2 Base Application Programming Reference

Differences

GDDM V3R2 Base Application Programming Reference
SC33-0868-02

The following paragraphs describe how GDDM calls from GDDM-REXX are implemented differently from calls from other programming languages.

Array parameters: Array parameters are treated more strictly in GDDM-REXX than they are in other high-level languages - in particular, arrays must be multi-dimensional when they describe lists of lists of values. You should be careful with calls where GDDM-REXX requires an array of strings, for example, GSPLNE. Other languages may accept all values concatenated in one string.

FSINIT: This call is not usually required in GDDM-REXX programs. If you do use it, it initializes a new instance of GDDM within the instance of GDDM-REXX, thereby making the program reentrant.

FSTERM: In GDDM-REXX programs, FSTERM is required only if the program is reentrant. It is used to terminate an instance of GDDM within the instance of GDDM-REXX.

If you use the GXGET AAB to open multiple instances of GDDM under the reentrant interface, FSTERM ends an instance.

Reentrant support: Reentrant support is provided by means of subcommands that extract and set the anchor block, rather than by a separate set of reentrant calls. These subcommands are GXGET AAB and GXSET AAB. They are described in "GDDM-REXX programming interface" in topic 6.0.

Mapping: The ERXMSVAR EXEC, and two subcommands GXSET MSVARS and GXSET MSADS, are provided so that maps created with GDDM-IMD can be used in REXX EXECs through GDDM mapping calls.

Mapping with GDDM-REXX is further described in "ERXMSVAR EXEC" in topic 6.6.

PA2 as escape to subset: By default in GDDM/VM, PA2 acts as an escape into subset mode. If CMS subset is entered in this way from a GDDM-REXX EXEC, it is not possible to use further EXECs that use GDDM-REXX.

PA2 is set by means of the CMSINTRP procopt. Processing options are discussed in "Processing options" in topic 19.0.

Note: Under MVS, PA2 causes a reshow.

GDDM-REXX EXECs in subset mode or invoked from other programs: If you plan to use GDDM-REXX EXECs from CMS subset mode, or if your GDDM-REXX EXECs are likely to be invoked from other programs,

the GDDM-REXX command module should be loaded in the nucleus with the following command:

NUCXLOAD GDDMREXX

When the GDDM-REXX exec has run, you can use the NUCXDROP command to free nucleus storage.

Termination on MVS: On MVS, GDDM-REXX is not automatically terminated when a EXEC ends. The programmer must ensure that a GDDMREXX TERM command is always executed before exiting from an EXEC. This includes exits cause by errors and by attention interrupts by the terminal user.

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