If you have created your own REXX parameter modules for your installation or have tailored the parameter modules (IRXREXX1, IRXREXX2, and IRXREXX3 respectively TSOREXX1, TSOREXX2 and TSOREXX3 for TSO/E 2.5 and lower) supplied by IBM®, you must add entries to the host command environment table defined in those modules, in order to access the new LINKPGM, ATTCHPGM, LINKMVS, and ATTCHMVS host command environments.