You access information in the PARM field of an EXEC statement by referring to the contents of general register 1. When control is given to the program, general register 1 contains the address of a fullword which, in turn, contains the address of the data area containing the information.
The data area consists of a halfword containing the count (in binary) of the number of information characters, followed by the information field. The information field is aligned to a fullword boundary. Figure 47 shows how the PARM field information is structured.
General register 1
*--------------------------------------*
*------------* Address of Fullword |
| *--------------------------------------*
| Points to
| *--------------------------------------*
*----------->| Address of Data Area *-----------*
*--------------------------------------* |
Points to |
*---------------------------------------------------------------*
|
| *-----------------*--------------------*
*----------->| Count in Binary | Information Field |
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