JES2 supports 3211 indexing through the specification of the INDEX parameter on the /*OUTPUT control statement, JCL OUTPUT statement, or in the extended FCB image. With the extended FCB image, JES2 supplies two special FCBs: FCB26 for 6 lines per inch and FCB28 for 8 lines per inch (specified as FCB=6 and FCB=8, respectively). These FCBs contain a channel 1 indication in position 1, a special index flag in the third byte, and the number of lines per inch in the fourth byte of the image. The special index flag in the third byte of FCB26 and FCB28 contains X'80' plus a binary index value, in the range of 1 to 32 (if not specified, 1 is the default). The index value sets the left margin (1 indicates flush-left position; other values cause indentation of the print line by n-1 positions).

For JES2 to use any other FCB images, they must specify channel 1 in position 1; otherwise, JES2 incorrectly positions the forms in the printer. (STD1 and STD2 do not specify channel 1 in position 1, therefore, you should not specify these for JES2 unless you alter them.) If the third byte of any other FCB image contains a data character (specifying the number of lines per inch) other than X'80', JES2 uses that specification and supplies an index value of 1.