Read-only env variable in PAM module

Hi guys, does anybody know how to set/create read-only environment variable inside PAM module? I've written my own pam authentication module and I'd need to pass some information to user application started by user after user has been logged to the system and user should not be allowed to change this information. I know that it is possible to set read only variable in shell using 'declare -r var' and I would need to achieve the similar functionality but inside pam module. I tred to use pam_misc_setenv() function but it does not have the possibility to set read only variable.

Thanks and regards,
Joaquin