New to me also, but a little digging produced this. The act of 28 Feb 61 (Prov. Cong. C.S.A., Stat.39, organizing the general staff of the Confederate Army) provided for a Commissary General's Office under a colonel. The Subsistence Dept. obtained provisions for the Army chiefly from the domestic output of the Confederacy. In 1861, it began purchasing meat in areas where the Army was undertaking operations. During 61-62, cattle were brought from TX and LA, but this source was cut off when US forces controlled the MS River. Salt was obtained from works in Saltville, VA, from salt mines on Avery Island near New Iberia, LA, and from evaporating basins along the coasts into which sea water was run. Both the salt basins and fisheries that were developed along the coast were easily raided by Federal gunboats. Commissary officers impressed subsistence stores and collected other supplies under legislation levying a tax in kind on agricultural produce.

In the field, operations of the Subsistence Dept were carried on by commissary officers and agents. Some of them worked directly under the Commissary Gen'ls Office, and others were attached to Army commands. They competed with each other and with the procurement officers of other War Dept bureaus in purchasing supplies. To correct this, a system of chief purchasing commissaries was introduced by a circular of 15 April 63, which assigned chief purchasing commissaries to each state.

The officer designated as chief commissary in Alabama was Major John J. Walker, in Mobile. Depots for storage of commissary supplies were maintained at several places, including Mobile and Selma.

The above is extracted from the Guide to the Archives of the Government of the Confederate States of America.