All the posting accounts are stored in SY01100. You can get them with the series, but the Posting Account Description seems more straight forward.
-- Drop stored procedure if it already exists
IF EXISTS (
SELECT *
FROM INFORMATION_SCHEMA.ROUTINES
WHERE SPECIFIC_SCHEMA = N'dbo'
AND SPECIFIC_NAME = N'DD_SY01100_SEL_byPostingAcctDesc'
)
DROP PROCEDURE dbo.DD_SY01100_SEL_byPostingAcctDesc
GO
CREATE PROCEDURE dbo.DD_SY01100_SEL_byPostingAcctDesc
-- DD_SY01100_SEL_byPostingAcctDesc
@PTGACDSC VARCHAR(31)
AS
select g5.ACTNUMST
from sy01100 p
left join gl00105 g5 on g5.actindx = p.actindx
WHERE P.PTGACDSC = @PTGACDSC
go
grant exec on DD_SY01100_SEL_byPostingAcctDesc to public
--sp_sps