Example

In the following example, the DSCB at actual-device address X'00 00 00 01 07' is returned in the virtual storage location READAREA, using the SEEK option. The DSCB resides on the volume with the volume serial number 108745.

          OBTAIN   ACTADDR         READ DSCB FROM
*                                  LOCATION SHOWN IN CCHHR
*                                  INTO STORAGE AT LOCATION
*                                  NAMED READAREA

ACTADDR   CAMLST   SEEK,CCHHR,VOLSER,READAREA
CCHHR     DC       XL5'0000000107' ABSOLUTE TRACK ADDRESS
VOLSER    DC       CL6'108745'     VOLUME SERIAL NUMBER
READAREA  DS       140C            140-BYTE WORK AREA

Recommendation: Check the return codes.

The OBTAIN macro points to the CAMLST parameter list. SEEK, the first operand of CAMLST, specifies that a DSCB be read into virtual storage. CCHHR specifies the storage location containing the 5-byte actual-device address of the DSCB. VOLSER specifies the storage location containing the serial number of the volume where the DSCB resides. READAREA specifies the storage location to which the 140-byte DSCB is to be returned.

Control is returned to your program at the next executable instruction following the OBTAIN macro instruction. If the DSCB has been read into your work area, register 15 contains zeros. Otherwise, register 15 contains one of the return codes shown in Table 1.