Use the OPEN macro to open a data set.

The format of the OPEN macro is:

label

specifies 1 to 8 characters that provide a symbolic address for the OPEN macro.

address

specifies the address of the ACB or DCB for the data sets being opened. You may specify the address either in register notation (using a register from 2 through 12, in parentheses) or with an expression that generates a valid relocatable A-type address constant. If you use register notation to open one data set, enclose the expression identifying the register within two sets of parentheses: OPEN ((2)).

options

specifies options parameters used only in opening non-VSAM data sets. VSAM ignores options specified with the address of an access method control block.

Because the OPEN parameters are positional, if options are not specified, you must insert a comma before coding a subsequent parameter.

MODE =

specifies the format of the OPEN parameter list being generated.

24

specifies that a standard form (24-bit) parameter list address be generated. The parameter list must reside below 16 megabytes and point to an ACB residing below 16 megabytes.

31

specifies that a long form (31-bit) parameter list address be generated. The parameter list can reside above 16 MB and can point to an ACB residing above 16 MB. This parameter value must be coded if the parameter list or the VSAM/VTAM ACB resides above 16 megabytes.

Rule: For non-RLS, if the VSAM control blocks and buffers are to reside above 16 megabytes, the RMODE31 parameter must be specified in the ACB before the OPEN is issued.