PATCH: Changing a control data set record

Explanation: PATCH is an optional parameter you specify to change a control data set record.

PATCH(offset) allows you to specify a decimal value anywhere from zero up to a number equal to the length of your CDS record, or an equivalent hexadecimal value, for the offset. Hexadecimal characters must be in the form X'n'. The variable data portion of the record is patched starting at the specified offset.

PATCH(data) allows you to substitute the changes you want made to the data. You can enter the data as hexadecimal characters or alphameric characters and $, #, or @. You can change up to 256 bytes of data.

PATCH(bits), allows you to substitute an eight-character string specifying which bit or bits you want turned on or off. A period (.) means do not change bit, a 1 means set bit on, and a 0 means set bit off. For example,

           0.1.....

means set bit 0 off and set bit 2 on and do not change bits 1, 3, 4, 5, 6, and 7.

PATCH GEN(nn) allows you to specify the original data set name, along with a generation number, instead of specifying the DFSMShsm-generated name for the backup version data set. When using the GEN(nn) parameter, the FIXCDS required parameter type must be ‘C’.

Abbreviations: None.

Defaults: If you do not specify one of the optional parameters of FIXCDS, the default is DISPLAY.

Note:

The offset of the first byte of the variable data of the record is zero.
The offset of the last byte of the variable data of the record is one less than the length of the variable data.
If you are patching an MCL record, the first two bytes of the record cannot be changed. This area contains the 43rd and 44th character of the data set name. If this area is specified to be patched, the FIXCDS command fails.
The results of using the FIXCDS command to patch the CDS records may not be permanent. There are situations when DFSMShsm logic may negate the patched field.