Well, I tried your test program, without linking to the special RL
(which Bill Cadier said worked for him), and it works for me also:

/l all
    1     program getenv (input, output);

    2
    3     TYPE
    4
    5     char_array = packed array [1..80] of char;
    6     char_star  = ^char_array;
    7
    8     VAR
    9
   10     env_name : char_star;
   11     envtoget : char_array;
   12
   13     FUNCTION getenv ( envname : char_array ):char_star;
   14     EXTERNAL;
   15
   16     BEGIN
   17
   18     envtoget := 'SERVER_NAME';
   19     envtoget[12] := CHR(0);
   20
   21     env_name := getenv (envtoget);
   22     IF env_name = NIL THEN
   23         writeln('getenv() call failed to get anything...')
   24     ELSE
   25         writeln('ENV_NAME = ', env_name^);
   26
   27     END.
/
set lang pasc
'Language' is now PASC
/kq  testenv
27 lines saved
/setvar server_name,'SYS1'
/pasxllk testenv,testprogg

PAGE   1  HP PASCAL/iX HP31502A.05.02    COPYRIGHT HEWLETT-PACKARD CO.
1986
          WED, MAY 31, 2000,  1:15 PM

    0     1.000   0   program getenv (input, output);
    0     2.000   0
    0     3.000   0   TYPE
    0     4.000   0
    0     5.000   0   char_array = packed array [1..80] of char;
    1     6.000   0   char_star  = ^char_array;
    2     7.000   0
    2     8.000   0   VAR
    2     9.000   0
    2    10.000   0   env_name : char_star;
    3    11.000   0   envtoget : char_array;
    4    12.000   0
    0    13.000   0   FUNCTION getenv ( envname : char_array
):char_star;
    0    14.000   0   EXTERNAL;
    0    15.000   0
    4    16.000   1   BEGIN
    4    17.000   1
    4    18.000   1   envtoget := 'SERVER_NAME';
    5    19.000   1   envtoget[12] := CHR(0);
    6    20.000   1
    6    21.000   1   env_name := getenv (envtoget);
    7    22.000   1   IF env_name = NIL THEN
    8    23.000   1       writeln('getenv() call failed to get
anything...')
    9    24.000   1   ELSE
    9    25.000   1       writeln('ENV_NAME = ', env_name^);
   10    26.000   1
   10    27.000   1   END.

     NUMBER OF ERRORS =  0     NUMBER OF WARNINGS =  0
     PROCESSOR TIME 0: 0: 0    ELAPSED TIME 0: 0: 3
     NUMBER OF LINES =   27    LINES/MINUTE =  5664.3
     NUMBER OF NOTES =    0
End Run
END OF COMPILE
HP Link Editor/iX (HP30315A.06.10) Copyright Hewlett-Packard Co 1986

LinkEd> link from=$oldpass;to=testprog

END OF LINK
/run testprog

ENV_NAME =
SYS1
End Run
/ e

END OF PROGRAM
Sys1:listf testprog,2
ACCOUNT=  SYN         GROUP=  FLEXUSER

FILENAME  CODE  ------------LOGICAL RECORD-----------  ----SPACE----
                  SIZE  TYP        EOF      LIMIT R/B  SECTORS #X MX

TESTPROG  NMPRG   128W  FB         119        119   1      128  1  *


Sys1:shell
CWD is "/SYN/FLEXUSER".
########################################################################


               MPE/iX Shell and Utilities (A.50.02)
    COPYRIGHT (c) Hewlett-Packard Company 1992, All Rights Reserved.

########################################################################


shell/iX> set
@="SH.HPBIN.SYS"
CIERROR="395"
CURRFKEYSET="1"
ENV="/SYN/FLEXUSER/.environ"
ERRNO="27"
...<deleted lines for brevity>...
SECURITYANSWER="0"
SERVER_NAME="SYS1"
TERM="hp2392a"
TZ="EST5EDT"
YPRINTER="0"
_="]"
_SH_CWD1="/SYN/FLEXUSER"
shell/iX>
./TESTPROG
ENV_NAME =
SYS1
shell/iX>

As you can see, I created a standard program file in an MPE group, and
it works in the CI as well as shell.  This was done on a 6.0 system.

However, there was recently a discussion about the problems using Pascal
input and output in a CGI program.  The paper on Jazz mentions that only
the READ and PRINT intrinsics should be used.  I would suggest rereading
the paper I mentioned earlier and trying the techniques in the sample
Pascal program.