The program returns the volume with the master catalog

/* REXX ***************************************************************/
/* Master Cat Info                                                    */
/**********************************************************************/
cvt      = Storage(10,4)                    /* Get the CVT address    */
amcbs    = Storage(D2x(256+C2d(cvt)),4)     /* Get the AMCBS address  */
acb      = Storage(D2x(8+C2d(amcbs)),4)     /* Get the ACB address    */
caxwa    = Storage(D2x(64+C2d(acb)),4)      /* Get the CAXWA address  */
dsncat   = Storage(D2x(52+C2d(caxwa)),44)   /* Dsn of Master Cat      */
dsncat   = Strip(dsncat,T)                  /*                        */
ucbcat   = Storage(D2x(28+C2d(caxwa)),4)    /* UCB name for Master Cat*/
volcat   = Storage(D2x(28+C2d(ucbcat)),6)   /* Volume for Master Cat  */
Say dsncat" on "volcat
exit