This gist comes from client requests to have a mechanism to "reset" environment variables within a job.

Reset environment variables in a job.sql

-- Subject: Reset environment variables in a job
-- Author: Scott Forstie  
-- Date  : January, 2024
-- Features Used : This Gist uses SQL PL, qsys2.ENVIRONMENT_VARIABLE_INFO, and qsys2.qcmdexc
--

--
-- When a job is started, it "inherits" all system level environment variables as job level environment variables.
-- From that point on, the job can add, change, and remove job level environment variables.
-- But... what should a job do if they want to reset or return to the initial state of environment variables?
-- The answer lies at the bottom of this gist...
--
-- Resources:
-- https://www.ibm.com/docs/en/i/7.5?topic=services-environment-variable-info-view
-- https://www.ibm.com/docs/en/i/7.5?topic=locale-using-environment-variables-set-active
-- The LANG environment variable is automatically created during job initiation 
--  when you specify a locale path name for the LOCALE parameter in your user profile or for the QLOCALE system value.
--
-- Note: The approach below does not compensate for additional JOB level environment variables appearing.
--       If the reset needs to also remove JOB level environment variables, this gist could be revised to establish a base 
--       understanding of the base set of job level envvars. Then, the reset processing would remove and/or reset those envvars.

stop;

--
-- What environment variables do I have established in this job?
--
select ENVIRONMENT_VARIABLE_NAME, ENVIRONMENT_VARIABLE_VALUE
  from QSYS2.ENVIRONMENT_VARIABLE_INFO
  where ENVIRONMENT_VARIABLE_TYPE = 'JOB'
  order by ENVIRONMENT_VARIABLE_NAME;
stop;

--
-- What system-level environment variables exist?
--
select ENVIRONMENT_VARIABLE_NAME, ENVIRONMENT_VARIABLE_VALUE
  from QSYS2.ENVIRONMENT_VARIABLE_INFO
  where ENVIRONMENT_VARIABLE_TYPE = 'SYSTEM'
  order by ENVIRONMENT_VARIABLE_NAME;
stop;


--
-- What environment variables does this job have, that do not exist at the sysstem-level?
--
select ENVIRONMENT_VARIABLE_NAME, ENVIRONMENT_VARIABLE_VALUE
  from QSYS2.ENVIRONMENT_VARIABLE_INFO
  where ENVIRONMENT_VARIABLE_TYPE = 'JOB' and
        ENVIRONMENT_VARIABLE_NAME not in (
          select ENVIRONMENT_VARIABLE_NAME
            from QSYS2.ENVIRONMENT_VARIABLE_INFO
            where ENVIRONMENT_VARIABLE_TYPE = 'SYSTEM')
  order by ENVIRONMENT_VARIABLE_NAME;
stop;


    
--
-- Remove job level environment variables that came from system level envvar inheritance
--
select qsys2.qcmdexc(
    'QSYS/RMVENVVAR ENVVAR(''' concat ENVIRONMENT_VARIABLE_NAME concat ''') LEVEL(*JOB)')
    as rmvenvvar_results
  from QSYS2.ENVIRONMENT_VARIABLE_INFO
  where ENVIRONMENT_VARIABLE_TYPE = 'JOB' and
        ENVIRONMENT_VARIABLE_NAME in (
          select ENVIRONMENT_VARIABLE_NAME
            from QSYS2.ENVIRONMENT_VARIABLE_INFO
            where ENVIRONMENT_VARIABLE_TYPE = 'SYSTEM')
  order by ENVIRONMENT_VARIABLE_NAME;
stop;

--
-- Re-review the job's envvars
--
SELECT ENVIRONMENT_VARIABLE_NAME, ENVIRONMENT_VARIABLE_VALUE 
    FROM QSYS2.ENVIRONMENT_VARIABLE_INFO
    WHERE ENVIRONMENT_VARIABLE_TYPE = 'JOB'
    order by ENVIRONMENT_VARIABLE_NAME;
stop;

--
-- Re-inherit the system level envvars
--
select
  qsys2.qcmdexc(
    'QSYS/ADDENVVAR ENVVAR(''' concat ENVIRONMENT_VARIABLE_NAME concat ''') VALUE(''' concat
      ENVIRONMENT_VARIABLE_VALUE concat ''') CCSID(*JOB) LEVEL(*JOB) REPLACE(*YES)')
    as addenvvar_results
  from QSYS2.ENVIRONMENT_VARIABLE_INFO
  where ENVIRONMENT_VARIABLE_TYPE = 'SYSTEM'
  order by ENVIRONMENT_VARIABLE_NAME;
stop;

--
-- Re-review the job's envvars
--
SELECT ENVIRONMENT_VARIABLE_NAME, ENVIRONMENT_VARIABLE_VALUE 
    FROM QSYS2.ENVIRONMENT_VARIABLE_INFO
    WHERE ENVIRONMENT_VARIABLE_TYPE = 'JOB'
    order by ENVIRONMENT_VARIABLE_NAME;
stop;

--
-- Bring the reset logic together in a procedure.
--
create or replace procedure Coolstuff.Reset_envvars ()
    not deterministic
    modifies sql data
    set option commit = *NONE, dynusrprf = *USER, usrprf = *USER
begin
--
-- Remove job level environment variables that came from system level envvar inheritance
--
  create or replace table qtemp.envvarrmv as
        (select
            qsys2.qcmdexc(
              'QSYS/RMVENVVAR ENVVAR(''' concat ENVIRONMENT_VARIABLE_NAME concat ''') LEVEL(*JOB)')
              as rmvenvvar_results
            from QSYS2.ENVIRONMENT_VARIABLE_INFO
            where ENVIRONMENT_VARIABLE_TYPE = 'JOB' and
                  ENVIRONMENT_VARIABLE_NAME in (select ENVIRONMENT_VARIABLE_NAME
                      from QSYS2.ENVIRONMENT_VARIABLE_INFO
                      where ENVIRONMENT_VARIABLE_TYPE = 'SYSTEM')
            order by ENVIRONMENT_VARIABLE_NAME)
        with data
    on replace delete rows;
--
-- Add all system evnvars as job level environment variables
--
  create or replace table qtemp.envvarrmv as
        (select
            qsys2.qcmdexc(
              'QSYS/ADDENVVAR ENVVAR(''' concat ENVIRONMENT_VARIABLE_NAME concat ''') VALUE('''
                concat ENVIRONMENT_VARIABLE_VALUE concat
                ''') CCSID(*JOB) LEVEL(*JOB) REPLACE(*YES)') as addenvvar_results
            from QSYS2.ENVIRONMENT_VARIABLE_INFO
            where ENVIRONMENT_VARIABLE_TYPE = 'SYSTEM'
            order by ENVIRONMENT_VARIABLE_NAME)
        with data
    on replace delete rows;
end;

--
-- Authorize any user to use this facility
--
grant all on procedure Coolstuff.Reset_envvars to public;
stop;

--
-- Reset the envvars in the current job
--
CALL Coolstuff.Reset_envvars();
stop;

--
-- Re-review the job's envvars
--
SELECT ENVIRONMENT_VARIABLE_NAME, ENVIRONMENT_VARIABLE_VALUE 
    FROM QSYS2.ENVIRONMENT_VARIABLE_INFO
    WHERE ENVIRONMENT_VARIABLE_TYPE = 'JOB'
    order by ENVIRONMENT_VARIABLE_NAME;

Pehaps this will make it complete:

SetEnvvar:
https://gist.github.com/NielsLiisberg/d33b4697c04078c32bea5d219aa49111

GetEnvVar:
https://gist.github.com/NielsLiisberg/093b9bc18b603abac5a297ec239aa690