To modify an FCB image in virtual storage before loading it into a forms control buffer, use the following sequence of macro instructions to read the FCB image into virtual storage.

1. An IMGLIB macro instruction, along with the OPEN parameter.
2. A BLDL macro instruction to determine if the FCB image is in the image library.
3. A LOAD macro instruction to load the image into virtual storage.
4. After the image has been read in, issue the IMGLIB macro instruction with the CLOSE. parameter and the address of the DCB built by the first IMGLIB macro.

A SETPRT macro instruction can be used to load the forms control buffer with the modified image. Printers other than the 3800 require the use of an FCB entry in an exit list, as described in z/OS DFSMS Using Data Sets.

The formats of the BLDL and SETPRT macros are given in z/OS DFSMS Macro Instructions for Data Sets; the format of the LOAD macro is given in z/OS MVS Programming: Assembler Services Guide and z/OS MVS Programming: Assembler Services Reference ABE-HSP.

The format of the IMGLIB macro is:

>>-+-------+--IMGLIB--+-OPEN-------+---------------------------><
   '-label-'          '-CLOSE,addr-'   

OPEN

Opens SYS1.IMAGELIB and specifies that a DCB is to be built for it. The address of the DCB is returned in register 1.

CLOSE

Closes SYS1.IMAGELIB.

addr

Specifies the RX-type address of a word that points to the DCB. If coded in the form (reg), the register in parentheses contains the address of the DCB, not the address of the word.