Characteristics of a Language Processor Environment - IBM-REXX

When IRXINIT initializes a language processor environment, IRXINIT creates several control blocks that contain information about the environment. One of the control blocks is the parameter block (PARMBLOCK). The parameter block contains the parameter values that IRXINIT used to define the environment, that is, the parameter block contains the characteristics that define the environment. The block also contains the addresses of the module name table, the host command environment table, and the function package table, which contain additional characteristics for the environment.

TSO/E provides three default parameters modules, which are load modules that contain the values for initializing language processor environments.The three default modules are IRXPARMS (MVS), IRXTSPRM (TSO/E), and IRXISPRM (ISPF). A parameters module consists of the parameter block (PARMBLOCK), the module name table, the host command environment table, and the function package table.This shows the format of the parameters module.

Overview of Parameters Module

Overview of Parameters Module

This shows the format of PARMBLOCK. Each field is described in more detail following the table. The end of the PARMBLOCK must be indicated by X'FFFFFFFFFFFFFFFF'. The format of the module name table, host command environment table, and function package table are described in subsequent topics.

Format of the Parameter Block (PARMBLOCK)

Format of the Parameter Block (PARMBLOCK)

The following information describes each field in the PARMBLOCK. If you change any of the default parameters modules that TSO/E provides or you use IRXINIT to initialize a language processor environment.

ID
An 8-byte character field that is used only to identify the parameter block that IRXINIT creates. The field name is ID.The value that TSO/E provides in the three default parameters modules is IRXPARMS. You must not change the value in the ID field in any of the parameters modules.

Version
A 4-byte character field that identifies the version of the parameter block for a particular release and level of TSO/E. The field name is VERSION.The value that TSO/E provides in the three default parameters modules is 0200. You must not change the Version field in any of the parameters modules.

Language Code
A 3-byte field that contains a language code.

The field name is LANGUAGE.The language code identifies the language in which REXX messages are displayed. The default that TSO/E provides in all three parameters modules is ENU, which is the language code for US English in mixed case (upper and lowercase). The possible values are:

  • CHS – Simplified Chinese v CHT – Traditional Chinese
  • DAN – Danish
  • DEU – German
  • ENP – US English in uppercase
  • ENU – US English in mixed case (upper and lowercase)
  • ESP – Spanish
  • FRA – French
  • JPN – Japanese (Kanji)
  • KOR – Korean
  • PTB – Brazilian Portuguese

Reserved
A 1-byte field that is reserved.

Module Name Table
A 4-byte field that contains the address of the module name table. The field name is MODNAMET.The table contains the ddnames for reading and writing data and for loading REXX execs, the names of several replaceable routines, and the names of several exit routines.

Host Command Environment Table
A 4-byte field that contains the address of the host command environment table. The field name is SUBCOMTB.

The table contains the names of the host command environments for processing host commands.These are the environments that REXX execs can specify using the ADDRESS instruction.The table also contains the names of the routines that are invoked to handle the processing of commands that are issued in each host command environment.

Function Package Table
A 4-byte field that contains the address of the function package table for function packages.

Token for PARSE SOURCE
An 8-byte character string that contains the value of a token that the PARSE SOURCE instruction uses.The field name is PARSETOK. The default that TSO/E provides in all three parameters modules is a blank. This token is the last token of the string that PARSE SOURCE returns. Every PARSE SOURCE instruction processed in the environment returns the token.

Flags
A fullword of bits that IRXINIT uses as flags. The field name is FLAGS.

The flags define certain characteristics for the new language processor environment and how the environment and execs running in the environment operate.In addition to the flags field, the parameter following the flags is a mask field that works together with the flags. The mask field is a string that has the same length as the flags field. Each bit position in the mask field corresponds to a bit position in the flags field. IRXINIT uses the mask field to determine whether it should use or ignore the corresponding flag bit.

The summarizes each flag. The mapping of the parameter block (PARMBLOCK) includes the mapping of the flags. TSO/E provides a mapping macro IRXPARMB for the parameter block. The mapping macro is in SYS1.MACLIB.

Summary of Each Flag Bit in the Parameters Module

Summary of Each Flag Bit in the Parameters Module

Mask
A fullword of bits that IRXINIT uses as a mask for the setting of the flag bits.The field name is MASKS. The mask field is a string that has the same length as the flags field. Each bit position in the mask field corresponds to a bit in the same position in the flags field. IRXINIT uses the mask field to determine whether it should use or ignore the corresponding flag bit. For a given bit position, if the value in the mask field is:

  • 0 — the corresponding bit in the flags field is ignored (that is, the bit is considered null)
  • 1 — the corresponding bit in the flags field is used.

Subpool Number
A fullword that specifies the number of the subpool (in binary) in which storage is allocated for the entire language processor environment. The field name is SUBPOOL. The default value in the IRXPARMS module is 0. The value can be from 0 to 127 in decimal. In the IRXTSPRM and IRXISPRM modules, the default is 78 (in decimal). For environments that are integrated into TSO/E, the subpool number must be 78.

Address Space Name
An 8-byte character field that specifies the name of the address space. The field name is ADDRSPN. TSO/E provides the following defaults:

  • IRXPARMS module – MVS
  • IRXTSPRM module – TSO/E
  • IRXISPRM module – ISPF

X'FFFFFFFFFFFFFFFF'
The end of the parameter block is indicated by X'FFFFFFFFFFFFFFFF'.

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